Digital Images for Humanities

Transcription

1 Digital Images for Humanities Oxford University Computing Services

2 How to Use This Book The Exercises This handbook accompanies the taught sessions for the course. Each section contains a brief overview of a topic for your reference and then one or more exercises. Exercises are arranged as follows: A title and brief overview of the tasks to be carried out A numbered set of tasks, together with a brief description of each A numbered set of detailed steps that will achieve each task Some exercises, particularly those within the same section, assume that you have completed earlier exercises. Your lecturer will direct you to the location of files that are needed for the exercises. If you have any problems with the text or the exercises, please ask the lecturer or one of the demonstrators for help. This book includes plenty of exercise activities more than can usually be completed during the hands-on sessions of the course. You should select some to try during the course, while the teacher and demonstrator(s) are around to guide you. Later, you may attend follow-up sessions at OUCS called Computer8, where you can continue work on the exercises, with some support from IT teachers. Other exercises are for you to try on your own, as a reminder or an extension of the work done during the course. Writing Conventions A number of conventions are used to help you to be clear about what you need to do in each step of a task. In general, the word press indicates you need to press a key on the keyboard. Click, choose or select refer to using the mouse and clicking on items on the screen (unless you have your own favourite way of operating screen features). Names of keys on the keyboard, for example the Enter (or Return) key, are shown like this ENTER. Multiple key names linked by a + (for example, CTRL+Z) indicate that the first key should be held down while the remaining keys are pressed; all keys can then be released together. Words and commands typed in by the user are shown like this. Labels and titles on the screen are shown like this. Drop-down menu options are indicated by the name of the options separated by a vertical bar, for example File Print. In this example you need to select the option Print from the File menu. To do this, click with the mouse button on the File menu name; move the cursor to Print; when Print is highlighted, click the mouse button again. A button to be clicked will look like this. The names of software packages are identified like this, and the names of files to be used like this. OUCS ii

3 Software Used Files Used Revision Information Version Date Author Changes made 1.0 February 2011 Dave Baker and Vicky Brown Created iii OUCS

4 Acknowledgements This workshop was developed jointly by the IT Learning Programme of Oxford University Computing Services and Humanities Division. Particular thanks to: Vicky Brown who contributed some of the text and images and offered encouragement in developing the session. Mike Heaney for sharing his expertise in copyright and agreeing to be recorded in a video used in support of this course. Steve Eyre for his creation of the above video. Copyright The ScannedImage.tiff file is used with the permission of Professor Ralph Weiss. It may only be used within the context of this course. The HighResolution.tiff file is used with the permission of Dave Baker. It is made available under a Creative Commons licence (Attribution-NonCommercial- ShareAlike CC BY-NC-SA) The ForImprovement.jpeg image is used with the permission of Dave Baker. It is made available under a Creative Commons licence (Attribution- NonCommercial-ShareAlike CC BY-NC-SA) The images used in the Picasa exercise are used with permission of their creators under Creative Commons licences. Thank you to Dietmut Teijgeman-Hansen and Martin Heigan. Screenshots are copyright of the respective software suppliers. The remainder of this document is copyright of Oxford University, Computing Services. OUCS iv

5 Contents 1 Introduction What you should already know What you will learn Where can I get a copy of the software? Image Discovery Image Collections at the University of Oxford Image resources via OXLIP Image subscription databases Image collections in the Bodleian Libraries & University Museums Image collections hosted elsewhere within the University Images on the Web Academic image collections on the web Stock image collections on the web Social network collections, other free image collections and using Image search engines Copyright & Licensing Image Creation What is a digital image? How is colour represented? Monochrome images Greyscale images Colour images Resolution Image Quality Image compression JPEG TIFF RAW + (DNG) PNG GIF BMP A comparison of image formats Digital cameras Scanning Scanning for print v OUCS

6 Scanning for display For Presentation Slides Scanned image format Scanning 35mm slides Image editors Image management and use Image organisation and cataloguing Web-based software Locally-based software Image organisers Image metadata Image tags and keywords Using images in your work Using web sourced images Using images from other documents Discovering an image s pixel count Using images in presentation tools Using images in word processed documents Keeping your images safe Preservation of the data Preservation of the format Ingestion and backup of images - a scenario Digital asset management and image archiving What Next? Other digital image sessions Computer OUCS Help Centre Downloadable course materials (WebLearn) Reference Material OUCS vi

7 Table of Exercises Exercise 1 Searching for images in ARTstor and Bridgeman... 4 Exercise 2 Discovering images on the web Exercise 3 Copyright & Creative Commons Licenses Exercise 4 Exploring image resolution and quality Exercise 5 Improving a scanned image Exercise 6 Improving an image Exercise 7 An introduction to Picasa Exercise 8 Using images in PowerPoint and in ARTstor OIV Exercise 9 Keeping your images safe vii OUCS

8

9 Digital images: a workshop DPIF/1 1 Introduction Welcome to the course Digital Images workshop! This booklet accompanies the course delivered by Oxford University Computing Services (OUCS), IT Learning Programme. Although the exercises are clearly explained so that you can work through them yourselves, you will find that it will help if you also attend the taught session where you can get advice from the teachers, demonstrators and even each other! If at any time you are not clear about any aspect of the course, please make sure you ask your teacher or demonstrator for some help. If you are away from the class, you can get help by from your teacher or from help@oucs.ox.ac.uk 1.1. What you should already know This session makes no assumptions about your existing knowledge of digital images. We will assume that you are familiar with using a computer and the basics of file management, such as opening files from particular folders and saving them, perhaps with a different name, back to the same or a different folder. The computer network in OUCS may differ slightly from that which you are used to in your College or Department; if you are confused by the differences ask for help from the teacher or demonstrators What you will learn This session is not a comprehensive coverage of all of the aspects of the discovery, creation and use of digital images; it is designed to draw your attention to some of the important issues and useful skills, and to point you in the right direction for further research and study. In this session we will cover the following topics: The availability and use of image collections Discovering images on the web Copyright and creative commons Scanning images Simple use of an image editor (GIMP) Image resolution and quality Image management software Using images in your work Keeping your images safe 1.3. Where can I get a copy of the software? Where possible, we have tried to use software that is either freely available on the Internet, or is widely available through University departments, or is commonly available on personal computers and laptops. 1 OUCS

10 DPIF/1 Digital images: a workshop 2 Image Discovery 2.1. Image Collections at the University of Oxford If you are not able to create your own images, or you prefer not to, you should investigate the various image collections that are available to you as an academic researcher and more generally. Collections fall into two types: those that you can use freely (although invariably with an attribution) and those that incur a cost per image, or per use of an image. An excellent resource offering advice on all aspects of image discovery is the following section on the JISC Digital Media web site at Whilst this particular article deals with other types of media as well as still images, it is a great way in to this vast topic. An important general point to remember when searching for visual media is that you will most commonly be using text to search for images, so resource discovery is reliant on the data that someone has associated with the particular object matching your search term Image resources via OXLIP+ Your prime source of information about image collections for your field of study is your departmental or college librarian. They will also be able to advise you about the conditions of use for images from particular collections. Searching OXLIP+ for databases relevant to your subject is no doubt something you are already familiar with and should be your first port of call. Image databases both those that the University pays a subscription for and those that are freely available will often be listed here by subject. These usually appear under the sub-category of Visual Resources or Image Databases. If there is nothing listed in your specific subject, you can try looking in others, for example, under Art and Architecture, there are 25 image databases listed which are not necessarily exclusive to this field of study. Intute, a subject gateway, is a free online academic service that evaluates academic resources and provides links to them from its web site. It covers all major subject areas and provides many links to image resources, including Humanities specific sites at Unfortunately, funding for this service has ceased and so there are no new resources being added, but it provides an invaluable way in to visual materials within sites and services which might not necessarily be picked up by regular search engines Image subscription databases Amongst the largest image databases with content specifically made for educational purposes are ARTstor and Bridgeman Education, both of which the University subscribes to and to which you therefore have free access. You will find them listed in OXLIP+ and if you are on the Oxford network, you can also access them directly at the following URLs: The content of both is wide-ranging (the ART in ARTstor is misleading) and together they provide access to at least one million high-quality images suitable for use in your papers and presentations, all at no cost to you. Whilst there are OUCS 2

11 Digital images: a workshop DPIF/1 occasional overlaps in terms of content, very often it is vastly different, so it is certainly worth exploring both databases. Should you wish to use images from these databases for publication, you will need to seek permission from the relevant provider: in the case of ARTstor, which is a collection of collections, each image has an image rights data field which should include the name of the rights holder and contact details. With regards to Bridgeman Education, the Bridgeman Art Library owns the rights to all images in this database and you would need to contact their London office (contact details are on the front page of the Bridgeman Education website). Training sessions which allow for a more in depth exploration of these databases, including their content and functionality, are held each term as part of the OUCS IT Learning Programme Image collections in the Bodleian Libraries & University Museums The University is fortunate to have its own rich resources, both textual and visual. Many of these are held by the Libraries in the form of their Special Collections much of which has been digitised. To explore these virtual collections, follow these links: digital.bodleian.ox.ac.uk/ or The Bodleian manuscripts and early printed books are also available via ARTstor. The University Museums obviously have a wealth of visual materials too, again much of which exist in a digital format and can be accessed via their websites (for Terms and Conditions of use, refer to each website). You can access the museums portal at Image collections hosted elsewhere within the University As with many other institutions, digitisation projects including visual material have been carried out elsewhere around the University. An example is the First World War Poetry Digital Archive hosted by OUCS: Other image archives are held within individual departments and colleges, some of which are listed on their websites and many of which exist only in analogue format. A lot of these are cross-disciplinary so are worth investigation. The History of Art Department has image collections across many analogue media, all of which have historically been made available to anyone at the University who uses images in their teaching and research: Further information about the photographic archive can be found here: tinyurl.com/62e8q66 Academic staff often have their own personal image archives of photographs and slides. These are unique resources which you are only likely to find out about via your Faculty and/or supervisor, unless they have decided to share them with a wider audience, such as the archives on the Khalili Research Centre website: krc.orient.ox.ac.uk/krc/index.php/image-archive A recent project at the University has recognised the need to pool information regarding digital activities, resources and facilities across the Humanities at Oxford. For further details, see: dighumdb.oerc.ox.ac.uk/default.aspx 3 OUCS

12 DPIF/1 Digital images: a workshop Exercise 1 Searching for images in ARTstor and Bridgeman Oxford researchers have access to two very large subscription image databases, specialising in high quality images (1 mil+) with differing content. These images are cleared for educational use. This exercise will give you a brief introduction to both. Launch ARTstor from OXLIP+ Register in ARTstor Carry out a simple search Open an image & related text Download image to desktop Save images to an image group & log out Launch Bridgeman Education from OXLIP+ Carry out a simple search Open image & download to desktop Add images to a slideshow & download to desktop Task 1 Launch ARTstor in OXLIP+ Launch web browser and connect to OXLIP+ oxlip-plus.ouls.ox.ac.uk Search for ARTstor by title Click on the entry for ARTstor. Task 2 Register in ARTstor In the Welcome to ARTstor pane click on Register Enter your address and a password and click on SUBMIT Task 3 Carry out a simple search In the SEARCH box type for example: russian revolution or petrarch or poster* or your own search term and hit GO Click on the drop down arrow next to Sort by and select Date Figure 1 Simple ARTstor search box OUCS 4

13 Digital images: a workshop DPIF/1 Task 4 Open an image & related text Double click on an image to open it and click on the image to zoom. Click on the image. button to pan around the zoomed Task 5 Download image to desktop Step 3 Click on the Step 4 Click on the again to hide it. Click on the button to return to normal size. button to show the image data and button to download the image. On the Terms and Conditions of Use pane select I accept. In the Save file dialogue box, navigate to the Desktop and click Save N.B. If you are still zoomed in on the image, this is the view that will be saved. Step 3 Minimise the browser window to view the desktop. You will see that two files have been downloaded the image as a jpeg and the corresponding metadata as an HTML file. Task 6 Save images to an image group and log-out From your earlier search, single click on thumbnails of images you are potentially interested in (click again to deselect). This can be done across multiple pages. Go to Organize Save selected images to New image group. Single click on My Work Folder and enter a name for your image group at the bottom of the dialogue box. Select Save Step 3 In the Welcome to ARTstor pane, click Log out. Confirm you want to log out by clicking Yes. 5 OUCS

14 DPIF/1 Digital images: a workshop Figure 2 Saving ARTstor images to a new image group Task 7 Launch Bridgeman Education from OXLIP+ Task 8 Carry out a simple search Task 9 Open image and download to desktop Launch a web browser and connect to OXLIP+ oxlip-plus.ouls.ox.ac.uk Search for Bridgeman Education by title Click on the entry for Bridgeman Education. In the Search box type for example: Russian revolution or petrarch or poster* or your own search term. Click Search Single click on an image to open it and click on N.B. This will work fine on some images, but not on others. Close the zoom window. Right mouse click on the image. Use Save image as, navigate to the Desktop and click Save Step 3 Minimise the browser to view the desktop. You will see that one file has been downloaded the image as a jpeg. OUCS 6

15 Digital images: a workshop DPIF/1 Task 10 Add images to a slideshow and download to your desktop Click on to return to the search results. Click on below images which you are interested in to save them to a slideshow Click on to download the current slideshow. Step 3 In the Slide Show Download pane, select the option: Download a zip file containing images and viewer Click Download Click Download the slideshow Step 4 In the dialogue box that opens, click on Save File Click OK and then click Save in the Save dialog. Step 5 Go to the desktop. You will see a zip folder BalEdSlideShowViewerxxx.zip Double click to open the folder and you will see your jpeg images. Step 6 Close the web browser in order to exit Bridgeman Education 2.2. Images on the Web The web provides an infinite quantity of digital visual materials, but how do we go about navigating this maze of opportunity? Again, JISC Digital Media have compiled a number of useful pages which go into vast amounts of detail, including A review of Image Search Engines at Finding Subject-Specific Digital Media Resources at Some FAQs on Can I Use Images Found on the Internet? at In this section, we will confine ourselves to looking at some other types of image collections available on the web, both with an academic but also a more public face. We will also look at the use of search engines to find content. 7 OUCS

16 DPIF/1 Digital images: a workshop Academic image collections on the web We looked at Intute in the previous section and it will come up again in the next exercise. Other directories that pull together academic resources include Google Directory. Here s a link to the libraries section, but there are many other equally potentially interesting ones to look at: directory.google.com/top/reference/libraries/special_collections/ Another resource which brings together collections with a more national focus is JISC Collections Catalogue: This allows you to filter by subject, academic level and resource type, in a similar way to Intute. Likewise another host for UK digitised academic collections from libraries and archives, which leans more towards the Visual Arts, is VADS: Whilst they proclaim to be the the online resource for visual arts, the collections included here could equally pertain to History, Politics and Literature. Other image collections with academic content that cover many subject areas across the Humanities and which are freely available for educational use are World Images: worldimages.sjsu.edu Luna Commons: David Rumsey Visual Collections (some overlap with Luna Commons): The NYPL Digital Library is another fantastic resource, which whilst naturally having quite a North American slant to it, does have an array of different media and subject areas: digitalgallery.nypl.org/nypldigital/explore/dgexplore.cfm?topic=all Swinging back towards Europe, Europeana seeks to bring together content from European Museums, Archives and Libraries: and whilst you cannot download content from here, how can we not include Google s latest foray into the world of art?: Stock image collections on the web Stock image collections are usually less formal than academic collections and cover a wider spread of topics. Traditionally a stock image collection held images from professional photographers which could be used on payment of a fee. Fees tended to be high (and still are for superior collections) and customers are usually advertising and media companies. With the widespread availability of digital cameras, there are now many stock image collections that are contributed to by a community of amateurs and semiprofessionals. The quality of the images is variable although many are excellent but the cost is more affordable to the casual user. Most stock image collections allow you to search for images not only by keyword, but also image features such as colour and orientation. OUCS 8

17 Digital images: a workshop DPIF/1 Some examples are: Commercial stock image collections The images here are from professional photographers and of very high quality. The costs are such that only frequent users of such images would find it viable (a typical account costs of the order of 150 per month). Images in this collection are contributed by a wide community of amateur and professional photographers. You are charged per image, and typically an image costs in the region of 1-5. The conditions of use are quite generous, but need to be read carefully if you yourself want to use an image in a commercial rather than an academic setting. Similar to, and a competitor of, istockphoto. A web site that searches many other, smaller, commercial stock image web sites. It offers a number of licensing options for images, but the costs are high, often in the range 10 to 100 for the use of a single image. The image quality is usually correspondingly high. Free image collections A relatively small collection of images that has a UK bias but with some images from elsewhere in the world. The images are free to use in a non-commercial environment as long as an attribution is included. A morgue file is a term used to describe an image that is available for reference and use in the newspaper industry. This site has a large collection of images, of variable quality, that can be used freely for noncommercial work. Out of courtesy, contributors usually ask for an stating what you are intending to use the image for. puts itself forward as the leading free stock photo site. It has a reasonably large collection, covering many topic areas, and is backed up by a good advanced search facility. Finally, there are the two commercial giants, Getty Images (including collections such as the Hulton Archive and Time and Life Pictures ) and Corbis (including the Bettmann Archive ): Social network collections, other free image collections and using Image search engines In this final section on searching images on the web, we will look at the phenomena of sharing images on the web and the use of image search engines to retrieve this content. Most people are aware of or have accounts on Flickr Flickr is an image sharing web site. Anyone can post their images and make them available for viewing publicly, or to a closed group. There are restrictions on free Flickr accounts, which are removed for a small annual payment. Many images in Flickr are made available under the Creative Commons licence, and so can be used in an academic environment (we will return to Creative Commons in the next section). There is no editorial control of the images and so the quality varies widely. You can also connect your flickr account to other Web 2.0 type applications such as Facebook, Twitter and blogs. Although popular, Flickr is not the only image hosting/ photo sharing site. Similar services include Photobucket and Kodak Gallery. Other image 9 OUCS

18 DPIF/1 Digital images: a workshop management software products like Google s Picasa (which we will look at in section 4 on Image Management and Use) also have an integrated photo sharing website. A subsection of Flickr, The Commons, contains material from the world s public photo collections from 46 institutions. All images have No known copyright restrictions. One of the key aims of this project is to encourage members of the public to contribute comments and tags to the images and so enrich the resource. There is a wealth of content here, potentially spanning many subject areas. Another free resource with public contributor content is Wikimedia Commons: commons.wikimedia.org Resources are not just limited to still images; video and sound is included here too. Whilst this is a vast and rich resource, we advise some caution: using images from here for private research and for inclusion in your theses is fine. Should you wish to publish images (including web publications and websites of course), be aware that copyright jurisdiction varies from country to country and there may be multiple restrictions that apply. Where possible, you may wish to contact the contributor for more information to find out more about its source and copyright status. The site has a whole page dedicated to using content outside of Wikimedia Commons: commons.wikimedia.org/wiki/commons:reusing_content_outside_wikimed ia The web is an image-rich environment. When you view a web page, the text and associated images are downloaded on to your computer and so it is very easy to capture an image and use it elsewhere; in most web browsers right-clicking on an image presents you with an option to place a copy of the image in a particular folder. Many search engines offer an image search feature, for example (the big three): images.google.co.uk and uk.images.search.yahoo.com/images where you can search for images by keyword. There are image dedicated search engines like which you can experiment with too. Images on the web are usually optimised so that they download quickly. As a result, the quality of web page images is rarely good enough for use in a high quality document or slide (though there are obviously exceptions to this, even in free sites like Wikimedia Commons). More to the point, images on web pages are invariably in copyright and so cannot be used elsewhere without the permission of the copyright holder. Some web pages expressly state that content is in copyright, however even if such a statement is missing, you must assume that copyright holds. Search engine providers recognise the importance of these issues and so some allow you to filter using their Advanced search option, allowing the searcher more control over image size, source and licensing information. OUCS 10

19 Digital images: a workshop DPIF/1 Exercise 2 Discovering images on the web It is unlikely that you will find everything you need in the image databases that the University subscribes to. The web provides limitless access to images aimed at different audiences. In this exercise, we will look at two possible methods that an academic researcher might use to retrieve images on the web: using a search engine and the Intute service Carry out a basic search using Google images Filter your search by size and medium Carry out the same search using the Advanced image search Open an image & note related text and rights notice Visit the Intute Humanities webpage Browse by subject area; browse by topic or search within subject area Filter by type (images) and visit one of the listed websites Task 1 Carry out a basic search using Google images Launch a web browser and in address bar type the following URL: Search for napoleon Bonaparte or your own search term. Task 2 Filter your search by size and/or medium In the pane on the left-hand side, under size select Larger than In the drop down list select 1024x768 In the pane on the left-hand side, under type select photo. Note the number of hits. Figure 3 Google image search with filtering 11 OUCS

20 DPIF/1 Digital images: a workshop Task 3 Carry out the same search using the Advanced image search Task 4 Open an image and note related text and rights notice Task 5 Visit the Intute Humanities webpage Task 6 Browse by subject area; browse by topic or search within subject area Below the search box on the right-hand side, click on Advanced search Under usage rights select reuse Click on More info for full definitions labelled for Use the browser back button to return to the Advanced Image Search interface and click on Google Search Note the number of hits Choose an image and click to open it Close the image preview window to view the image on its page. Scroll down to view file size details and any other image data supplied by the contributor. Scroll down further to read the Licensing information. Open a new tab or window in your web browser and in the address bar, type the following URL: N.B. The site is no longer being added to. It is nevertheless a powerful resource worth investigating. Note the Virtual Training Suite for Humanities Under Browse Humanities select a subject area. In the new window that opens, select a sub-topic under Browse... or carry out a keyword search in the Search... dialogue box OUCS 12

21 Digital images: a workshop DPIF/1 Figure 4 Intute browse by subject Task 7 Filter by type (images) & visit one of the listed websites If you chose to browse by sub-topic, in the new window, under Filter by type, select Images and then click Search. If you carried out a keyword search, under Filter by resource type, select Images. Scroll down to view the webpages listed. Select one and follow the link to that site (which will open in a new window). Take a few minutes to explore the site and/or return to Intute and open another of the listed sites. Close the web-browser to end your session Copyright & Licensing Firstly a disclaimer! The authors are not experts in copyright law and the discussions here and elsewhere in this document are their interpretations of the issues involved. For accurate advice, you should firstly contact your librarian, who will be able to guide you or suggest someone else who can help you. The video interview relating to copyright which is shown as part of this course is intended to give you a brief introduction to this topic. Another good place to start is the JISC Digital Media website: and in particular the section devoted to copyright and digital images: There are also some FAQs relating to copyright guidance offered by the University s Library Services: 13 OUCS

22 DPIF/1 Digital images: a workshop More in depth legal advice is available via the following: JISC Legal provides Legal Guidance for ICT Use in Education, Research and External Engagement at The Intellectual Property Office gives the official line on UK copyright law: In some academic environments there is a tendency not to take legal issues such as copyright as seriously as they should be taken. This is especially so in countries which have a fair use clause to their copyright laws. Fair use covers the use of others work in a way that would not normally be considered an infringement of their rights. It is a notoriously difficult legal area particularly where digital images are concerned. The exact definition of fair use and the associated copyright laws differ from one country to another, and the blurring of international boundaries on the World Wide Web creates extra difficulties. Copyright and fair use are two-edged swords; not only do we need to be careful when using other peoples images, but also we may want to make sure that our own images are not misused. Incidentally, there is a common misconception that images placed on the Web are not subject to copyright. Every image on the web is subject to copyright unless it states otherwise. Even if it states that the image is copyright free, you need to make sure that the person making the statement is actually in a position to make it! Copyright sets out in law the rights a person has in safeguarding his or her creative work it is essentially the rights to copy a person s handiwork. The foundation of copyright law was laid in the 17th century specifically to protect printed works but, particularly over the last 30 years, has had to evolve to handle many other media formats, including digital images. Any creative work falls within the realms of copyright and so this includes your digital photographs. Although the exact details of the protection vary from one country to another, the Berne Convention lays down some core rights, which from a digital imaging perspective include: The exclusive right to reproduce the image. Some countries allow limited fair use for education and research without permission; in the UK this is usually referred to as fair dealing. The right to authorise a public performance of the image, what we might more commonly call an exhibition in an image context. The right to authorise an arrangement or adaptation of the image. The exclusive right to adapt or alter the image. The right to claim authorship. The right to object to a use of the image which could be prejudicial to the person s honour or reputation. Copyright is automatic; there is no legal requirement to assert your right. It is common practice however to include a copyright statement and the copyright symbol when an image is reproduced. This makes it clear that the image is copyright and who the copyright holder is. OUCS 14

23 Digital images: a workshop DPIF/1 Digital images fall into the copyright category of artistic works. The Berne Convention states that these works are protected for at least 25 years from creation and in the UK, copyright law extends this to the life of the author plus 70 years for works created since August Copyright law can be a difficult to interpret for any creative work, but digital photography introduces some unique problems. In a digital image we can faithfully reproduce other creative works in their entirety. This has similarities with photocopying. However, a digital image can include another person s work as a part of its own creative content. Furthermore, it is possible to take an existing digital image and apply various transformations, up to the point where the original is beyond recognition. Different creative works can have different copyright conditions associated with them, in which case a digital image of another creative work may have more than one type of copyright legislation involved. This is why the advice of someone well versed in copyright law can be invaluable. In the UK, much of copyright law is as yet untested in respect of digital image reproduction. It is also important to realise that copyright is only one aspect of personal rights that arise from digital images. Other concerns can be: Issues of personal privacy The inclusion of children in photographs Trademarks Design and typography rights Obscenity and decency within the context of a country s culture Once the copyright period for a digital image (or any creative work) has expired, it is considered to be in the public domain. Public domain works can be freely used and adapted without permission or even attribution. It is possible for the author of a work to place it into the public domain at any time by abandoning copyright. There is no set way to do this, other than the author making an explicit statement to that effect. This might be as simple as the statement The author of this work makes no claim of copyright. Once something is in the public domain, then you have no control over its use. Someone could take a public domain image, make a change to a single pixel and then claim it as their work and profit from it. A better course of action is to use a copyleft statement, or make use of the increasingly popular Creative Commons licences. Copyleft has no legal meaning, but is usually taken to mean a licence to use and distribute the work freely within certain clearly defined limitations. Typically this involves allowing people to adapt and distribute a work for non-commercial purposes providing the adapted and/or distributed work is also governed by the same conditions. Recently, a more formal statement of copyleft has been developed under the Creative Commons licensing system. There are a number of variations of Creative Commons licences which specify to different levels what is allowed with the work. For example: Attribution: Allows others to use and adapt your work, even commercially, providing you are given attribution as the original author. 15 OUCS

24 DPIF/1 Digital images: a workshop whereas Attribution Non-commercial No Derivatives: Allows others to use and distribute your work unaltered providing it is not used commercially and you are attributed as the author. Full information is available at: Clearly you need to be careful that you comply with any copyright and licensing specified for images that you obtain from elsewhere, but it is just as important that you assert your own conditions for the digital images that you make available to others. You are at liberty to attach your own conditions of use to your images, but you may need to take legal advice to get the wording correct; the Creative Commons web site contains suitable statements that you can use to invoke their licences. In the previous section, we started looking at means of searching for images on the web including the use of search engines, portal services such as Intute and how to better manipulate advanced search facilities to carry out more accurate, inclusive and safe searching. We have discussed Creative Commons and in fact, it is possible to search for reusable content from within the Creative Commons website, or by installing their add-on or plug-in into your web-browser of choice or using other browser add-ons like Open Attribute (currently available only for Firefox and Chrome): search.creativecommons.org/ openattribute.com/ OUCS 16

25 Digital images: a workshop DPIF/1 Exercise 3 Copyright & Creative Commons Licenses In this exercise, we will consider the use of licensing to search for images on the web (begun in Exercise 2 when filtering for images labelled for reuse ). We will search for images licensed under Creative Commons, a set of simple to use and standardized licences made freely available for anyone contributing content to the web, to indicate what can and cannot be done with it. We will also search for content in Flickr Commons. Carry out a Creative Commons search across search services such as Google, flickr, Wikimedia Commons etc. Compare content across search providers View an image s file size and licensing details In flickr tab, filter by Flickr Commons Observe copyright notice and follow link to main page View list of contributing organisations & browse/search a photostream Task 1 Carry out a Creative Commons search across search services such as Google, Flickr, Wikimedia Commons etc. Task 2 Compare content across search providers Launch a web browser and in the address bar type the following URL: search.creativecommons.org/ In the search bar, enter queen victoria or your own search term. Note that in the top banner, I want something that I can... defaults to use for commercial purposes and modify, adapt & build upon. Deselect one or both if you wish. Click on the Google (web), Google (image), flickr (image) and Wikimedia Commons tabs in turn and compare the search results. Note that in each case, your search is being filtered for content that can be used according to the terms you stipulated at the beginning of your search and/or for Creative Commons-licensed content. Task 3 View an image s file size and licensing details Choose an image in any of the search providers windows and click to open it. Look for any metadata, including file size and licensing details. 17 OUCS

26 DPIF/1 Digital images: a workshop Figure 5 Search for Creative Commons licensed images Task 4 In the Flickr tab, filter by Flickr Commons Task 5 Observe copyright notice and follow link to main page Select the flickr (image) tab. In the search box, click on the drop down arrow and select The Commons and then click SEARCH. Open an image by clicking on it. On the right-hand side, scroll down to view the License information. N.B. All images in Flickr Commons are marked No known copyright restrictions. Click on? next to this information to go to the Commons usage page. Note the Rights Statement and disclaimer. OUCS 18

27 Digital images: a workshop DPIF/1 Figure 6 Viewing an image in Flickr Commons Task 6 View list of contributing organisations and browse/search a photostream Scroll down the same page to see the list of Participating Institutions. Select one and click on the corresponding icon to take you to the Collection s photostream. You may choose to simply browse the images page by page, or browse by Collections, Sets, Galleries, Tags etc. see linked headings under the Photostream title. N.B. Not all headings are populated. Alternatively, you can search a collection s photostream by typing in a search string into the search box at the top right-hand side of the page. Step 3 Closer your web browser to end the session. 19 OUCS

28 DPIF/1 Digital images: a workshop 3 Image Creation There are many opportunities for creating images: Digital cameras Scanners Image creation and editing software We will briefly look at all three of these areas, but first we need to understand a little about digital images themselves What is a digital image? A digital image is a series of dots arranged in a regular grid. We often refer to these dots as pixels (picture elements) but for our purposes the terms are interchangeable. Each has a colour value (see below) and is of a size such that from a viewing distance they merge together to form an image. Pixels on a monitor screen are fractions of a millimetre in size. Printed image pixels can be much smaller than that, and pixels for large displays, at say a sports stadium, can be centimetres in size. The more pixels we have available in an image, the more we are able to represent fine detail. Images can range in size from a few hundred pixels wide and high, to several thousand pixels on a side. Even modest digital cameras can produce image sizes of something like 2560 pixels x1920 pixels, so the total number of pixels is: 2560 x 1920 = 6,635,520 Image sizes are usually measured in millions of pixels, or megapixels so this figure would usually be stated as 6.6 megapixels (6.6 MP). This does mean that digital image file sizes can be very large, and often compression is used to reduce the size (see below) How is colour represented? Each pixel in an image has a colour value. The range of this colour value determines the colours that can be represented Monochrome images If the colour value of a pixel has the range 0 to 1, then we can only represent two colours - one colour and its absence, so usually white and black. This means that each pixel can be represented by a one or a zero and the resulting file size is small. But of course, this is only suitable for simple line art Greyscale images Allowing the colour value to span the range 0 to 255 lets us represent shades of black from white through progressively darker greys to black. Each pixel is then represented by a byte of data (eight 1 s and 0 s) and so the image file size is much bigger in fact eight times as large as a corresponding monochrome image Colour images The way colour is represented depends on whether the image is destined for display (on a monitor or screen) or for print. There are a number of different ways colour can be represented, we will focus on two. OUCS 20

29 Digital images: a workshop DPIF/1 Display Colour Displays use the additive (RGB) model for producing colour. Varying amounts of Red, Green and Blue are used to produce the desired colour (Figure 7), with no colour giving black, and full strength colour of all three components giving white. Most commonly, each component can take a value from 0-255, so each pixel requires 3 bytes to represent the colour. This is referred to as a 24-bit colour space (each byte requiring 8 bits). With 24-bit colour, we can represent: 256 Red shades x 256 Green shades x 256 Blue shades = 16,777,216 colours 16 million colours is more than the human eye can distinguish, but we should appreciate that this colour space is evenly distributed, whereas the human eye is more sensitive to certain colours and hues. Therefore there has been a move to 48-bit colour in some areas of colour management for example in optical scanners. 48-bit colour uses 16 bits for each component to give the total number of colours that can be represented to be 281,474,976,710,656 (65,536 x 65,536 x 65,536), far in excess of what our eyes can detect. Additive (display) Subtractive (print) Print Colour Figure 7 Representing Colour Printing uses a subtractive colour model (CMYK). Inks on the paper absorb (subtract) certain colours leaving the remaining colours to be reflected back to the reader. The ink colours used are Cyan, Magenta and Yellow, which used in varying quantities can reproduce the range of colours. In theory using all three at full colour would result in all colours being absorbed producing Black. In practice we get a muddy dark brown! Therefore a forth ink, Black is also used. Display vs Print Colours The range of colours produced by the RGB model is not the same as those produced by the CMYK model. Although it is possible to closely match most RGB 21 OUCS

30 DPIF/1 Digital images: a workshop colours with a corresponding CMYK colour, this is not trivial and requires crosscalibration of the monitor, printer, paper and inks. In practice when printing an RGB image using CMYK inks the difference is not great, but if you do need to match colours exactly then you need to consult the person who will be printing the image Resolution Some ink jet printers that are used to produce photo-quality prints use extra ink colours on special paper to guarantee high quality colour matching. Resolution is usually taken to mean the amount of detail represented in the image, and this is directly related to the number of pixels. Display Resolution This is the number of pixels that are available on the display. A typical computer monitor might have a resolution of 1280 x 1024 pixels. If an image with fewer pixels is presented on the display, then it will only occupy a part of the screen unless the software enlarges it. Resizing an image can affect the quality (see below). If an image has more pixels than are available on the display, then only part of the image will be shown. Again, the image can be resized to fit, with the possibility of a loss of detail. Print Resolution Resolution on the printed page is measured in dots per inch (dpi, occasionally dpcm or dots per centimetre)). Good quality print requires about 200 dpi, high quality print about 300 dpi. To determine the optimum size for a digital image, you need to know the image dimensions in pixels and then divide by the required print resolution. So an image that is 1200 pixels wide could be printed high quality at: print size = 4 inches If you want to print at a larger size at the same resolution, then there are not enough pixels and the software will need to make up (interpolate ) extra, resulting in a degraded image. If you want to print at a smaller size there are too many pixels and the software will reduce the number, with a possible loss of detail. Scanner Resolution Scanner resolution is also measured in dots per inch. During the scanning process the image (slide, negative, journal page, etc.) is converted into our grid of colour valued dots at the scanner resolution that you choose. Typically scanners have a maximum resolution of 2400 or 4800 dpi. This high value enables small images, such as photographic negatives to be scanned and then printed much larger at good resolution. If we have a photographic slide that has a long side of 1.5 inches and we scan at 2400 dpi then: number of dots = 1.5 inches x 2400 dpi = 3600 dots If we then want to print at a print resolution of 300 dpi: OUCS 22

31 Digital images: a workshop DPIF/1 long side print size = =12 inches 3.4. Image Quality Image quality is in many respects subjective. It is affected by three aspects of the digital image workflow: Capture Processing Output Capture At the capture stage, the quality of the image is determined by the skill of the operator and the properties of the capture device. For a camera, the photographer can control the focus and lighting, the aperture and shutter speed, all of which can impact the quality of the image. At the same time, the optical quality of the lens (and whether it is clean or not!) and the properties of the sensor will influence the image. For a scanner, we need to consider the cleanliness of the glass platen the document sits on, the state of the document itself, and the placing of the document in the correct position. Processing Processing actually begins at the capture stage when the image from the sensor is converted into a data file representing the pixels. There are a number of formats that might be used (see below), some of which involve compression (also see below) and this can affect the image. As can subsequent image correction, editing and conversion to other formats. Output If the output for our image is a computer display then, assuming that the brightness and contrast have been adjusted correctly, the quality is affected mostly by the screen resolution and our choice of image size. The optimum visual quality is achieved when the image is displayed dot-for-dot, i.e. if the image is 100 pixels wide it occupies 100 pixels width of the screen. If we use fewer display pixels (to get a smaller on-screen image), then some pixels will be omitted or averaged and so reducing the amount of detail. If we use more display pixels, then some image pixels occupy more than one display pixels and the image looses its sharpness. For good quality printed output we clearly need good quality ink and paper. We also need to make sure that we are using the correct print resolution of at least 200 dpi Image compression The simplest way to store the pixels for a digital image is as a sequential list of numbers, with each number representing the colour value of a pixel. In addition it would be necessary to store a little extra information, such as the image width and height in pixels. If we consider 24-bit colour, then each pixel requires 3 bytes (a byte is 8 bits). Therefore even a modest image, of the order of say 2,000 pixels wide by 1,600 pixels high would require: 23 OUCS

32 DPIF/1 Digital images: a workshop JPEG 2,000 x 1,600 x 3 = 9,600,000 bytes or approaching 10 MB of storage. Some image formats do store the image in this way (see below), but more typically a format enables the data to be compressed, i.e. reduced in size. There are two types of compression: lossless and lossy In lossless compression, the data is processed to take up less space, but in such a way that no image information is lost or altered. On the other hand, lossy compression not only reduces the size of the image data, but in doing so changes some of the image detail, to achieve much higher compression ratios. The type of compression chosen is therefore a compromise between preserving all the image information and reducing the image file size. The JPEG (Joint Photographers Expert Group) format is by far the most widely used in digital cameras. This is primarily because it is very efficient in terms of storage size. The JPEG format is lossy. It makes use of complex algorithms to represent patterns of pixels as mathematical equations. This can produce significant savings in terms of file size; JPEG files can be as little as 10% of the original image data size. The down side of this is that the algorithms can change the values of some pixels. The JPEG algorithms can be tuned to give the amount of compression desired; the smaller the amount of compression, the fewer the number of pixels that are altered. This tuning is often represented as either a quality factor or a compression factor. Quality factors run from 0 to 100, with 0 being poor quality and 100 being high quality. Compression factors run from 100 to 0, with 100 being high compression and 0 being low compression. They mean the same thing, but some software uses one, some software uses the other. The values are for guidance only; a value of 50 in one digital image editor may not correspond to a value of 50 in another. Note that a compression value of 0 (or quality factor of 100) does not mean that there is no compression; the JPEG format always applies some compression, and so always alters some data in the image. Despite the lossy compression, the JPEG format is very useful and, when used with care, quite capable of producing images of satisfactory quality. When using the format, you need to watch out for the effects of the lossy compression, and decide for yourself whether or not they are acceptable. These effects are often referred to as JPEG artefacts. They are particularly noticeable at sharp edges in the image, for example around text. The following figure shows how an image can be affected by increasing the compression in the JPEG format: OUCS 24

33 Digital images: a workshop DPIF/1 Figure 8 Compression of a JPEG image TIFF You need to be aware that whenever you open a JPEG image in an image editor, and then resave the image, you risk eroding the quality. It is good practice to keep the original image (perhaps in another format) and always work on a copy, going back to the original for a fresh copy when appropriate. Simply opening and then closing (without using Save or Save As) will not affect the image. JPEG images are particularly effective for on-screen display, especially in web pages. Defects in the image are less noticeable on screens with their lower resolution (when compared to printing) and the smaller file sizes result in quicker display and download. There is a revised JPEG standard, JPEG2000, with even better compression, and with the option of lossless compression. However, this standard has not been widely adopted and is not encountered very often. The TIFF format, or more precisely the Tagged Image File (TIF) Format, is widely used, particularly in the commercial printing world. There are a number of variations but the two most common, and almost universally recognised, are TIF (uncompressed) and TIF (LZW). TIFF uncompressed images are large; indeed they can be larger than the original bit file since extra information such as a thumbnail of the image can be included. The TIF LZW format is used most often. LZW (Lempel-Ziv-Welch) is a compression algorithm developed in the 1970s. The algorithm is efficient, but lossless, and so cannot achieve the same compression ratios as JPEG. However all the image detail is preserved unchanged. Typically an image in TIF format is 70-90% of the original size. 25 OUCS

34 DPIF/1 Digital images: a workshop With the falling cost of data storage, it is now quite feasible to keep an original of an image in TIF format, and then use that to produce another format (perhaps JPEG) as and when required. It is worth noting that the LZW algorithm works by finding patterns within the image data. This proves to be very effective for 24-bit images, but in 48-bit images the variations in the image data are so great that the LZW algorithms can actually INCREASE the file size. Most web browsers will not display TIFF images without the help of a plug-in such as QuickTime RAW + (DNG) PNG Compact digital cameras invariably provide images in JPEG format (see above). This is mainly because memory was relatively expensive and more JPEG images could be stored in the camera than could other formats. The price of memory has fallen substantially, but compact cameras are now offering much higher image resolutions and so JPEG is still used to provide the capability for holding many images. On the other hand, professional and semi-professional camera manufacturers expect the user to invest in adequate storage, and most offer the option of storing images in a lossless format. TIFF (see above) is often one of the options, but another common one is RAW. The RAW format saves the data exactly as it was recorded by the image sensors in the camera, with little or no processing. This can result in very large image files, particularly for high resolution cameras. The advantage of RAW files is that, with the right software, it is possible to process the data in a much more controlled way, to the extent that even badly exposed images can often be recovered to provide acceptable results. As well as the size issue, the other problem with RAW is that there is not as yet an accepted RAW standard; each camera manufacturer has their own, which they change (improve) periodically. It is in the manufacturers interest to encourage use of their own RAW file format, so most make details available to the image editor software producers, but there can be a lag between the camera going on sale and the software being updated. Some manufacturers supply their own image editing software for use with their cameras. There is a move by Adobe to produce a standard RAW format, referred to as DNG (digital negative). We can hope that this is adopted widely in the future. In the meantime TIFF might be a more transportable format for longer term preservation of images. Adobe have made available a utility that converts virtually any RAW file into its DNG format. You can download the most recent version from the Adobe website (search for DNG Convertor). RAW images are not recognised by web browsers. The PNG (Portable Network Graphics) format is often overlooked. This is unfortunate because technically it is superior to TIFF. PNG supports lossless compression, and the algorithms used are better than TIFF resulting in files that are often 25% smaller than the TIFF equivalent. The technical features available in PNG have to a large extent been ignored by camera manufacturers and the image editor developers, and support for the standard is not as widespread as TIFF or JPEG. This is slowly improving. One area where PNG is becoming widespread is in web pages. It was originally OUCS 26

35 Digital images: a workshop DPIF/ GIF BMP developed to replace the GIF (Graphics Interface Format) standard used for line art and simple web graphics that was covered by a commercial patent. The PNG standard does support 48-bit images, but this aspect is not always implemented in image editors. The GIF (Graphics Interchange Format) standard was developed primarily to enable simple graphics to be included in web pages. Although it is still commonly used, it is slowly being replaced by PNG. Although GIF is very efficient for simple graphics, and does enable multiple frames to simulate animation, it is not generally suitable for digital images in that it has a limited colour space, supporting only 8 bit colours. BMP stands for bitmap, and is more a general term rather than a specific standard. It usually means an image format with the data stored as individual pixel values. Therefore most image formats, including TIF and JPEG are bitmaps. There is a specific Windows BMP format, which applies some simple compression in specific cases, but it is no longer widely used. Windows BMP are not recognised by many browsers and Mac users can have trouble using them A comparison of image formats For a full comparison of the technical details of various image formats, a good starting point is: en.wikipedia.org/wiki/comparison_of_graphics_file_formats Format Lossy Lossless Web friendly Common extension Max Colour depth (bits) Metadata JPEG jpg jpeg 24 TIFF tif tiff 48 RAW various 48 DNG dng 48 PNG png 64 GIF gif 8 BMP bmp 32 The following values are for an image taken on a high resolution camera. The conversions were done using GIMP (apart from the RAW to TIFF initial conversion). 27 OUCS

36 DPIF/1 Digital images: a workshop Format Size (KB) Comment TIF (48 bit LZW) 84,974 This compressed version is larger than the original. This is due to the LZW algorithm not being suitable for 48 bit images. TIF (48 bit) 70,788 NEF (Nikon RAW) 27,947 This RAW format clearly has some compression element to it TIF (24 bit LZW) 11,401 JPEG (100) 4,345 Although the impact on the image quality is almost imperceptible to the eye, information has been lost. JPEG (75) 1,378 JPEG (30) 235 At this level of compression, JPEG artefacts are clearly visible JPEG (0) 125 With this amount of compression, the image is almost unrecognisable! OUCS 28

37 Digital images: a workshop DPIF/1 Exercise 4 Exploring image resolution and quality In this exercise we will use a high resolution, high quality image. We will reduce the resolution, and so the file size, then re-enlarge it to see the effect. We will then look at a common lossy format, JPEG, and see the effect of quality reduction on file size. Open the high resolution image Examine the image properties Scale the image to be smaller Examine the image properties Scale the image back to its original size Compare with the original image Investigate the Quality/File size compromise of the JPEG format. Task 1 Open the high resolution image Double-click on the GIMP icon. Use File Open to display the Open Image dialog. Identify the HighResolution.tiff file in the Session Files folder. Click on it to select it. Click Open. Task 2 Examine the image properties Use Image Image Properties to open the Image Properties dialog. In the space below, make a note of the image properties, and then click Close. Pixel dimensions: File size: Size in memory: Number of pixels Task 3 Scale the image to be Use Image Scale Image to open the Scale Image dialog. 29 OUCS

38 DPIF/1 Digital images: a workshop smaller By default the image size is given in Pixels. Change the width of the image to 360 Task 4 Examine the image properties Press TAB or ENTER. Notice that the Height of the image is automatically changed to preserve the aspect ratio. This image size is typical of what might be used on a web page. Step 3 Ignore the X and Y resolution values. This is only applicable when the image is printed, and even then is often ignored by many applications. Step 4 Click on the Interpolation drop-down arrow. Notice that there are four options for interpolation. We will choose the default, Cubic. Click Scale. Step 5 Use File Save As to display the File Save dialog. In the Name text box type HighResolution360x270.tiff Click Save. Step 6 The Save As TIFF dialog will appear. TIFF is a loss less format, but can be used with different compression techniques. The most widely supported is LZW. Select the LZW option and click Save. Use Image Image Properties to open the Image Properties dialog. In the space below, make a note of the image properties, and then click Close. Compare the values with the original values. Pixel dimensions: File size: Size in memory: Number of pixels OUCS 30

39 Digital images: a workshop DPIF/1 Task 5 Scale the image back to its original size Task 6 Compare with the original image Task 7 Investigate the Quality/File size compromise of the JPEG format Use Image Scale Image to open the Scale Image dialog. Change the Width back to its original value: 3648 Click on the Scale button. Use View Zoom 1:1 to view the image at its full size. Only part of the image will be displayed. Use File Open to display the Open Image dialog. Select the original image HighResolution.tiff and click the Open button. A second image window will open. Step 3 Use View Zoom 1:1 to view the image at its full size. Step 4 Compare the two images. You should see a significant loss of detail in the rescaled image. Make sure you understand why this is. If you are not sure, ask the class teacher to explain. Step 5 Use File Close to close each image in turn. Do not save the images when prompted Use File Open and select the HighResolution360x270.tiff image. Click the Open button. Use View Zoom 2:1 to zoom into the image. Use View Shrink Wrap to enlarge the image window to the size of the image. Step 3 Use File Save As to open the Save Image dialog. Change the extension on the file name from tiff to jpeg Click the Save button. The Save as JPEG dialog will appear (Figure 9). 31 OUCS

40 DPIF/1 Digital images: a workshop Step 4 Rearrange the position of the windows so that you can see the image. Figure 9 The Save as JPEG dialog Step 5 Move the Quality slider all the way to the right to change the value to 100. Click to put a tick in the Show preview in image window tick box. Step 6 Note the File size shown: Step 7 Focus on some of the fine detail in the image (for example the masts to the left of the statue) Slowly move the Quality slider to the left. Step 8 Note the Quality value at which you start to see degradation of the image: Step 9 Note the File size at this point: 0 What do you consider is an acceptable compromise between Quality and File size? OUCS 32

41 Digital images: a workshop DPIF/1 Task 8 Click on the Save button. Use File Quit to close GIMP Digital cameras One way to ensure that an image serves a particular purpose is to compose it yourself using a digital camera. Most digital cameras have a point-and-shoot mode that makes taking acceptable images relatively easy. Those images which are not quite what was hoped for in terms of composition or technical quality can sometimes subsequently be rescued using an image editor. Once the image has been captured, it can be transferred to your own computer by either: or 3.7. Scanning Directly connecting the camera to the computer (usually through a USB lead) and then using software supplied with the camera to manage the transfer Removing the storage media from the camera, inserting it in a corresponding slot on our computer, or a card reader attached to the computer, and then using the computer file management software to copy the image from the media to local storage. The second method is usually preferred; it gives you greater control over the management of your images, and it does not deplete the battery of the camera. A scanner usually consists of a glass platen on which the existing image (print or transparency) is laid face-down, and through which a bright light is shone to illuminate the image. A cover is lowered to exclude ambient light. A light-detecting element then moves backwards and forwards in front of the illuminated image, recording the image as a grid of pixels. Scanners usually have proprietary software, supplied by the scanner manufacturer, which is used to control the scanning process. The software packages differ in the way they are used and you should consult your local IT help for the details. There is however a number of points that are important no matter what software you are using: Always use the best possible image source. For example, each time an image is photocopied, there is some degradation and this can be accentuated by the image scanning process. If possible, use the original rather than a photocopy. Remove any markings or blemishes on the source if you can. Make sure the glass platen is clean. Choose the correct scanning resolution. This is discussed below. Save in the correct image format, probably TIF. If necessary, correct the scanned image using image editing software. Getting the most out of the scanner requires some pre-planning. In particular you need to decide whether the image is to be displayed on-screen or in print and at 33 OUCS

42 DPIF/1 Digital images: a workshop what size. Many users of scanners simply position the image on the platen and then choose the highest quality scan settings that are possible. This often leads to images that are large both in terms of how they appear on the page/screen and in the storage space that they occupy. The technical details that govern the process and the settings required to get the optimal image are not always obvious. An excellent resource that covers this in detail is Wayne Fulton s ScanTips web site and book ( on which the following discussion is based. Once you have your scanned image, you may need to use an image editing tool to further enhance the quality Scanning for print Scanning software typically ask for the resolution that you want to scan at, measured in dpi (dots per inch). That is to say, a value of 300 dpi will result in an image having 300 dots for every linear inch. Printers also measure their output quality in dpi. A typical laser printer will print at 600 dpi or more. However, as Fulton says printer ink dots and image pixels are simply very different things. It is the conversion between scanned dpi and printed dpi that needs some thought. Printers do not print shades of grey (or shades of any other colour for that matter); they either print a black dot or no dot at all. To obtain a shade, a grid of dots is printed, with the dots dithered to produce the illusion of a shade. The diagram below shows a simplified version of this. On the left is a printed white pixel, in the middle is a printed grey pixel, and on the right is a printed black pixel (in reality printers are often able to vary the dot size and dither pattern to obtain subtler results). Figure 10 Printing shades of colour From the diagram, you can see that to reproduce one pixel in the image can take many dots on the printed page. The exact scaling factor is not straightforward to arrive at in that it depends on the printer type, printer resolution, dithering pattern, number of colours used etc. (see Fulton s web site for a full discussion) and an approximation is usually good enough. For a 600 dpi printer an image resolution of 150 to 200 dpi is often quoted as acceptable, so you can see that a factor of about four is used, and our diagram above is not too far off the mark. We will follow through an example of a 10x8 image that we want to reproduce at 5x4 on a page in a document printed on a 600 dpi laser printer. To print the image at 5x4, assuming that our 600 dpi printer requires 200 dpi images for good quality printing, we need an image size of (5 inches x 200 dpi) wide x (4 inches x 200 dpi) high or 1000 dots x 800 dots OUCS 34

43 Digital images: a workshop DPIF/1 To get 1000x800 dots from our 10x8 image, we need to scan at a resolution of 1000 dots / 10 inches (or 800 dots / 8 inches) which is 100 dpi Therefore our scanner settings are: resolution 100 dpi (or closest value greater than that) image size 5x4 inches You may need to use a custom settings option within the scanner software to get the opportunity to specify the values you want. You may also have the opportunity to adjust other aspects such as colour balance and contrast (often a matter of trial and error) Scanning for display A display screens are made up of a fixed grid of display dots (often also called pixels); a typical high resolution screen may have a grid of 1200x900 pixels. Each pixel is capable of displaying any colour (to an approximation, the exact details of the technology vary) and so we do not have to employ the dithering technique we saw for printing. We can therefore have a direct correspondence between the number of dots in the image and the number of dots on the display screen. In our example above our scanned image had 1000x800 dots and so would occupy a large part of the screen. If we wanted the image to be only half the width of the screen, then we would require an image that was sized at 600x450 dots. To get 600 dots from a 10 inch wide image we only need to scan at 60 dpi For Presentation Slides Presentation software such as PowerPoint has a dual nature, Although primarily designed for the delivery of images on a screen, the design process for individual slides uses a printed page metaphor. Therefore when you are scanning an image for use on a slide, you need to decide how large that image will be on the slide page. By default, a PowerPoint page is 10 x 7.5 inches (or 25.4 x 19 cm). Returning to our 10x8 image, let s say you decide that it should be 7.5 x 6 inches (retaining the aspect ratio 5:4 to avoid distorting the image) on a PowerPoint slide. PowerPoint prefers images to be in one of two resolutions. For on screen presentations it recommends 150 dpi. For slides that are to be printed (perhaps as transparencies for a standard overhead projector) it recommends 200 dpi. We will assume you are going to use this presentation on screen and so 150 dpi is appropriate. The pixel size that your image for the slide should be is: (7.5 inches x 150 dpi) wide x (6 inches x 150 dpi) high or 1125 dots x 900 dots To get 1125 dots from our source image that is 10 inches wide, we need to scan at 1125 dots /10 inches 35 OUCS

44 DPIF/1 Digital images: a workshop or dpi Therefore our scanner settings are: resolution dpi (or closest larger value, probably 120 dpi) image size 7.5x6 inches Impress (and other) presentation software does not quote preferred dpi for onscreen and printing, but the PowerPoint values are a good rule of thumb Scanned image format Just as with all image manipulation tools, scanned images can be saved in many different formats. The most common format is JPEG and it is tempting to use this format for your scanned images. However, JPEG is a lossy format; it does not preserve all the detail in the image. If you want to guarantee the maximum detail in your scanned images, you should use the TIF format. TIF is not as efficient as JPEG in terms of compression, but it is lossless ; none of the detail is lost. TIF images are compatible with most word-processing and presentation applications, but are not suitable for use on web pages. TIF images can always be converted to JPEG images later. Clearly, converting JPEG to TIF at a later time would not reintroduce detail that was lost in the original creation of the JPEG image. If in doubt, you can save the scanned image in both formats and compare the two for suitability for its final use Scanning 35mm slides It is possible to scan 35mm slides using a flatbed scanner; many scanners are supplied with an adaptor to make this easier. The principles are the same as discussed above but in addition: The small size of the images means that you will need to scan at a high resolution. For optimal quality, particularly if you are scanning the slides to create a digital archive, you may need to use a slide scanner rather than a flatbed scanner. Slide scanners can be expensive. For anything other than small quantities, it may be more effective to use a commercial slide scanning service. Dust on a slide can be very obvious on the scanned result, so it is especially important to clean the slide before scanning. Slides, particularly older slides, can be quite delicate, so use a blower brush (see the image below). If in doubt, seek professional advice. Figure 11 Blower brush OUCS 36

45 Digital images: a workshop DPIF/1 Exercise 5 Improving a scanned image The image we will use in this exercise is an actual example of a poorly scanned document. There was no opportunity to rescan the document and so we will enhance it as much as we are able. Note that in these situations there is always a compromise between removing noise and preserving detail. Open the image Use the despeckle feature to remove some of the background noise Enhance the contrast using the curves tool Save as a new file Compare with the original image Task 1 Open the image Double-click on the GIMP icon. Use File Open to display the Open Image dialog. Identify the ScannedImage.tiff file in the Session Files folder. Click on it to select it. Click Open. Task 2 Use the despeckle feature to remove some of the background noise Use Filters Enhance Despeckle to open the Despeckle dialog. Adjust the controls to see what effect they have. We are aiming to reduce the intensity and structure of the dots (speckles) in the background of the image, but retain the clarity of the letters. You can use the Preview tickbox to toggle between the original and despeckled preview. You can click and drag the four-headed cursor symbol in the bottom right corner of the preview image to adjust the area of the image that is previewed Step 3 Set the values to those shown in Figure 12. These were arrived at by experiment. Each image would need different values. Click OK. 37 OUCS

46 DPIF/1 Digital images: a workshop Figure 12 The Despeckle dialog Task 3 Enhance the contrast using the curves tool Use View Zoom 1:1 to enlarge the image to full size. Use Colours Curves to open the Curves dialog. Step 3 The Curves dialog shows the distribution of light and dark pixels in the image. We want to lighten the grey (despeckled) areas of the image, and enhance the darker text. This is similar to adjusting the brightness/contrast, but the curves tool gives us greater control. OUCS 38

47 Digital images: a workshop DPIF/1 Step 4 You can change the shape of the curve by clicking on a point on the curve and dragging it. Experiment with changing the shape. You can toggle the Preview state by using the Preview tickbox. You can reset the curve by clicking on the Reset button. Step 5 Adjust the curve so that it is similar to the one shown in Figure 13 This shape was chosen by experiment. Different images will be enhanced by different curve shapes. Click OK. Figure 13 The Curves dialog Task 4 Save as a new file Use File Save As to open the Save Image dialog Navigate to the Sessions Files folder. Save the file as ScannedImageEnhanced.tiff 39 OUCS

48 DPIF/1 Digital images: a workshop Step 3 The Save As TIFF dialog will appear. TIFF is a loss less format, but can be used with different compression techniques. The most widely supported is LZW. Select the LZW option and click Save. Task 5 Compare the image with the original Use View Zoom 1:8 to display the whole image in the image window. Use File Open Recent to display a list of recent files. Select ScannedImage.tiff Step 3 Adjust the position of the image windows to enable you to compare the two images Step 4 Use File Quit to quit GIMP Image editors Most applications which enable you to embed images in slide shows or documents also allow some limited image editing. These features are often restricted to the standard five: Resizing: Resizing an image can have a significant effect on its quality. In the figure below, you can see the effect of making an image smaller or larger. In the former, pixels are merged or lost whereas in the latter extra pixels are generated (interpolation). The degree to which a particular image is affected depends a lot on the image itself; the final arbiter is how the image looks when finally displayed or printed. Also take care when resizing an image that you retain the aspect ratio (width:height) so that the image is not distorted (unless this is the effect you want). OUCS 40

49 Digital images: a workshop DPIF/1 Figure 14 The effect of resizing a bitmapped image Cropping: This involves removing or hiding a strip of the image at one or more of its edges. Many images can be improved by cropping so that the viewer s attention is focused on the important features. In most applications, cropping does not remove that portion of the image, it is still there but hidden, (and contributing to the size of the file). The advantage of this is that you can uncrop the image should you want to. Rotating: If you are taking an image directly from a camera or scanner, it is useful to be able to rotate an image so that it is the right way up. Rotation of images by quarter-turns rarely degrades the image quality, but it is sometimes possible to see degradation with other rotation values. Mirroring: Sometimes referred to as flipping, this can be done along the vertical or horizontal axes of the image. This is sometimes useful to achieve a more aesthetically pleasing effect. Adjusting brightness and contrast: This enables you to change the amount of white added to colours to increase the apparent brightness, and increase or decrease the difference between the dark and light areas of the image to change the contrast. For more sophisticated image manipulation it is worth becoming familiar with the tools available in image editors such as GIMP or Photoshop. Extra features that you might find in image editors include: Filters: Filters are generally used to affect the whole image in a corrective or creative way. The term comes from the filters that photographers sometimes place in front of their camera lens to achieve a special effect. Some filters can be used to enhance an image. For example, an unsharp mask filter can be used to subtly improve the sharpness of an image although it cannot fix images that are out of focus! Other filters are purely creative. For example an orange filter can be 41 OUCS

50 DPIF/1 Digital images: a workshop used to warm the colours in an image. Other creative filters can totally transform an image by adding special effects. Curves: Adjusting the brightness (amount of white) or contrast (the difference between dark and light areas) in images is often too crude in that it affects all parts of the image equally. A curves tool allows you to change the darkness/lightness of pixels based on their current darkness/lightness. For example we can make dark pixels lighter without affecting pixels that are already light. Cloning and healing: Images often contain blemishes. These are often caused by dust in the capture process, but equally they could be other unwanted artefacts in the image such as a pencil mark on a scanned document, or some litter in the foreground of a scenic landscape. Cloning and healing tools allow you to selectively replace areas of an image with appropriate pixels sampled from other parts of the image. Layers: Applying corrections to an image usually changes the colour values of pixels permanently (and so you should always keep a copy of your images). Some image editing tools enable you to layer changes and corrections on top of the original image and so make nondestructive alterations that can be selectively applied or not. OUCS 42

51 Digital images: a workshop DPIF/1 Exercise 6 Improving an image In this exercise we will use a poorly composed and poorly exposed image and improve it using some of the tools common to all image editors. Open the image Straighten the image Crop the image to achieve a better composition Adjust the image thresholds to improve the image colours Save the image Task 1 Open the image Double-click on the GIMP icon. Use File Open to display the Open Image dialog. Identify the ForImprovement.jpeg file in the Session Files folder. Click on it to select it. Click Open. Task 2 Straighten the image Create a guideline by clicking and dragging within the ruler at the left of the image window towards the centre of the image. Release the mouse button when the guide is roughly centred in the image. In the GIMP Toolbox, click on the Rotate Tool (Figure 15). Step 3 With the Rotate Tool selected, click anywhere within the image. The Rotate dialog will be displayed. Step 4 Slowly move the Rotate slider to the left. Rotate the image so that the pillar between the two windows is vertical. Use the guideline to help judge this You can finely adjust the angle by changing the value in the Angle text box. A value of about -3.0 should work. Click on the Rotate button. 43 OUCS

52 DPIF/1 Digital images: a workshop Figure 15 The GIMP Toolbox, Rotate Tool Task 3 Crop the image to achieve a better composition In the GIMP Toolbox, click on the Crop Tool. The Crop Tool is the one to the left of the Rotate Tool. In the GIMP Toolbox, put a tick in the Fixed tickbox. The value next to the Fixed tickbox should be Aspect ratio. Step 3 Click and drag inside the image window to create a Crop area. You can resize the crop area by clicking and dragging in any of the four corners of the area. You can move the crop area by clicking and dragging inside the area. OUCS 44

53 Digital images: a workshop DPIF/1 Step 4 Achieve a satisfactory image by resizing and moving the crop image as you see fit. One possible choice is shown in Figure 16. Step 5 Click inside the crop area to perform the crop. If necessary you can undo the crop by using CTRL+Z (CMD+Z on a Mac). Figure 16 Possible choice of crop area Task 4 Adjust the image thresholds to improve the image colours Use Colours Levels to display the Levels dialog. The Levels dialog shows the distribution of the colour values in the image. Correctly exposed images generally have a histogram that spans the entire range. In this case the values are confined to about half of the range. Step 3 We can adjust this by moving the White point and Black point markers by clicking and dragging them along the axis. Do this and position them as shown in Figure 17. (Your histogram may look slightly different) Click OK. 45 OUCS

54 DPIF/1 Digital images: a workshop Figure 17 GIMP Levels dialog Task 5 Save the image Use File Save as to open the Save Image dialog. Save the image as improved.jpeg. If an Export File dialog appears, click on the Export button. Step 3 In the Save as JPEG dialog, use a Quality of 85 and click on Save. Step 4 Use File Quit to quit GIMP. OUCS 46

55 Digital images: a workshop DPIF/1 4 Image management and use One view of the digital image workflow is that it has five main areas Capture Correction and adaptation Organisation and cataloguing Use Backup and archival In the previous sections of this booklet, we have looked at aspects of the first two areas when we considered image discovery and image creation. We now briefly address the other three areas Image organisation and cataloguing Two of the advantages of a digital camera are that the results are instantly available and the recording medium can be re-used almost indefinitely. This means that digital camera users have the freedom to take as many images as they can accommodate on their computer disks or network storage. Combine this with the facts that images are becoming easier to download from elsewhere (such as stock image collections) and that we often have a need for images to be available on demand for presentations, web pages, brochures, reports and other documents, it is clear that we can have a significant file management problem. There are many different software applications available to manage images. Broadly they fall into two categories: web-based software which you use through any standard web browser locally installed software Many applications are aimed at the casual user and hobbyist. If you are in the position of managing large numbers of digital images, perhaps for a department, you should investigate professional, digital asset management (DAM) tools. In this section we are concerned with the management of your own images, perhaps as an aspect of your research, or for personal interest Web-based software There are a number of advantages in using web-based software: It can be accessed from any computer that has an internet connection it is not usually necessary to install anything on the local computer other than a modern web browser. This means that you have the potential for uploading and managing your images when you are away from your college or department. The software is generally platform independent it works through a web browser, and so if you move from a Windows PC to a Mac, you would not have to purchase new software. It is easy to give access to your images to individuals, groups or everyone. This can be useful from a social aspect but also academically; you can share images with colleagues without having to use OUCS

56 DPIF/1 Digital images: a workshop Flickr Much of the web-based software is freely available, although sometimes the functionality is restricted until a small fee is paid, and sometimes you have to endure adverts being juxtaposed with your images. Images are stored remotely and so loss or damage to your computer does not mean that you loose your image collection. You are of course relying on the integrity of the service provider in looking after your images, and it is your decision as to whether you need a separate, independent backup. Perhaps the most widely used image sharing web site is Flickr. You can sign up with Flickr for free and receive a monthly upload quota allowing you to store and distribute your images. Paying an annual membership fee removes the quota and also enables some extra features. Flickr, as with most web-based software, is constantly evolving and is now much more than a simple image sharing site. For example it allows you to associate images with places on a map of the world, or overlay a particular image with hotspots that can be used to annotate the image. The Social Web Web sites that enable sharing of information between informal groups are now widely used. Two popular examples of social networking sites are In addition to making communication and socialising easier, social networking sites also act as repositories for images. This is usually on a more casual basis than photo-sharing sites such as Flickr, and the image handling features are generally less sophisticated Locally-based software There is a large choice in software that you can install on your own computer to help in the management of your own image collections. You may even find that software is supplied with your camera, although this is often a lite version to entice you into purchasing the full version at a later date. The features of the software are very similar to those offered by web-based software. The main advantage is speed there is no delay while images are downloaded in to a web browser. Capacity is usually limited only by your own storage space, however you do need to bear in mind that backup is your responsibility and so you need sufficient safe storage away from your computer to store copies of all images effectively at least doubling your overall storage requirements. We will draw a distinction between software that is concerned with managing your images on a daily basis, here termed image organisers, and software that is concerned with archiving images for long term preservation Image organisers The range of software is constantly changing, as is the perception of what is best. Most software of this type is made available for a particular platform, usually Windows or Mac OSX. If you need software which is available for both, you are restricted much more. OUCS 48

57 Digital images: a workshop DPIF/1 Below are references to some commonly used image organising software. Picasa (Windows, Mac) This is made available by Google, and as you might expect integrates well with their wide-ranging web-based applications, including a web-based photo album. The software is downloaded form the Google web site and installed locally. There is no cost, but the software is financed by advertising and offering commercial printing services. picasa.google.com iphoto (Mac) This is supplied with Mac OSX. It integrates well with the other components of the ilife suite of programs and also with OSX in general. Aperture (Mac) Aperture is much more than an image organiser; it is also a powerful image editing program. It integrates well with other Mac applications. It is commercial software, but students and academics can purchase it at reduced cost. Album Shaper (Mac, Windows, Linux) This is one of very few truly cross-platform image organisers. It also includes some image enhancement tools. The software is open source and available under the GNU GPL licence and as such can be downloaded and used freely. albumshaper.sourceforge.net IMatch (Windows) This is another product that is far more than a simple image organiser, allowing image editing and web-based albums as well. It is commercial software but relatively inexpensive. PicaJet (Windows) This focuses solely on image organisation and offers very flexible categorisation of images. It is relatively inexpensive. It also offers a family licence so that the software can be installed on multiple computers in a single household. Adobe Lightroom (Windows, Mac) This is designed to work closely with Adobe s Photoshop image editing program. It manages images and will carry out some image adjustments, but you can also switch back and forth between Lightroom and Photoshop. It is relatively expensive in comparison with some other tools, but has the advantage of being the same on Windows and Mac. Microsoft Expression Media (Windows, Mac) A fully featured image management tool that is available for Mac and Windows. This product is aimed at the semi-professional and professional digital image user. It integrates well with the main image editing applications Image metadata With the advent of full text searching in Windows, Mac and other systems, text files became largely self-documenting. If you are looking for a document that you wrote about, say, climate change, you could search for every document containing that phrase. 49 OUCS

58 DPIF/1 Digital images: a workshop The same is not true of images. We will see that it is possible to extract some information from an image file, but this is generally limited to technical details (aperture and shutter speed) and time and date; there is limited opportunity to include details of what the image is about. This means that we usually need an external system for tagging, or attaching keywords to, our images so that we can do simple searches. Some popular image formats, such as JPEG, TIFF, DNG and (most) RAW, allow for additional information to be embedded within the image file. This is usually referred to as metadata (information about the image information). The Exchange Image File format (Exif) is a standard method of doing this. An example of Exif data (taken from the Exif Wikipedia entry) is: Tag Value Tag Value Manufacturer CASIO Components Configuration Model QV-4000 Compressed Bits per Pixel Y Cb Cr Orientation top - left Exposure Bias 0.0 Software Ver1.01 MaxApertureValue 2.00 Date and Time 2003:08:11 16:45:32 Metering Mode Pattern YCbCr Positioning centered Flash Flash did not fire. Compression JPEG compression Focal Length 20.1 mm x-resolution MakerNote 432 bytes unknown data y-resolution FlashPixVersion FlashPix Version 1.0 Resolution Unit Inch Color Space srgb Exposure Time 1/659 sec. PixelXDimension 2240 FNumber f/4.0 PixelYDimension 1680 ExposureProgram Normal program File Source DSC Exif Version Exif Version 2.1 Interoperability Index R98 Date and Time (original) Date and Time (digitized) 2003:08:11 16:45:32 Interoperability Version 2003:08:11 16:45:32 (null) OUCS 50

59 Digital images: a workshop DPIF/1 This information can be very useful when looking back at images to check the camera parameters and time and date, but it contains no information about the image content. It should be noted that the Exif standard can be used and interpreted differently by different camera and software manufacturers. This sometimes leads to difficulties, particularly if an image undergoes processing in several different software applications. Most image management programs enable you to examine the Exif data for an image, some allow you to change it. The information is also available through some file management utilities such as Windows Explorer and Mac Finder. Some software enables you to edit Exif data, and include your own (limited) information. There are other metadata formats. Two of note are: IPTC Information Interchange Model This was originally developed for use by news organisations but has also been adopted by some stock photo agencies and has been enhanced over time XMP This is an XML based standard developed by Adobe and which incorporates much of the IPTC standard Not all image editing software is able to manage all of the meta data formats and this does make it difficult to rely on metadata if the image is likely to be processed by different software packages. An example of a program that edits metadata is Reveal, it is available for both Windows and Mac OSX. Reveal is a single purpose utility; it only allows viewing and editing of image metadata and has some limitations but it is nonetheless useful. Reveal is available from: Windows version: albumshaper.sourceforge.net/ Mac OSX version: Image tags and keywords We have seen that it is possible to include limited information, in the form of keywords, in an image s metadata. This means that the keywords are available when we distribute the image, and are searchable. Most image management tools will make use of Exif and other types of metadata, but they usually keep track of images using a database held within the software. The simplest form of image management is the use of image tagging. Essentially this is the same as using keywords, and is referred to as such by some software, but we will use the term tagging to indicate that the metadata is kept externally (within the image management software package) rather than in the image itself. Careful use of tagging can greatly improve the ease with which we can find either a particular image that we can remember, but not recall the file name and/or location, or a selection of images that might satisfy a purpose we have in mind. It is important that we are consistent in the tags we use for images otherwise we will have problems in searching. For example, should we search for car or automobile, or more subtly car or cars. In a research project it is customary to decide on the list of tags ahead of time, and stick rigorously to the list. For personal use you can usually be more relaxed, but most image cataloguing applications will prompt you with tags that you have used previously. 51 OUCS

60 DPIF/1 Digital images: a workshop Exercise 7 An introduction to Picasa There are many image management applications available. Here we will take a brief look at some of the features in Picasa. Picasa is freely downloadable from the Google website, and is available for Windows and Mac. The install program has already been downloaded for you. Install Picasa Browse the found images Investigate the slide show option Create an album (virtual folder) Explore the Tags panel Search for tagged images Export an image Close Picasa Task 1 Install Picasa Task 2 Browse the found images Find the Picasa setup file icon in the Session Files folder and double-click on it. If prompted, confirm that you want to run the file. After a short delay the Setup wizard will start. Licence agreements are important, but for this exercise simply click on I Agree Step 3 Accept the default install location by clicking Install Step 4 Leave all the options in the final setup screen as they are and click Finish Picasa should start after a short delay. Step 5 Picasa will offer to scan the computer for images. Select the option to Only search My Documents, My Pictures and the Desktop Click Continue Step 6 If the Photo Viewer Configuration dialog is displayed, leave all options as they are and click Finish. By default, Picasa organises images by date and then by folder name. Click on the Martin Heigan folder under the 2006 heading. The images in the folder are displayed in the main part of the Picasa window. OUCS 52

61 Digital images: a workshop DPIF/1 Task 3 Create an album (virtual folder) Select the Dietmar Teijgeman-Hansen folder. At the head of the Library panel on the left of the Picasa window, click on the Create a new album button. In the Album Properties dialog (Figure 18), in the Name text box type Swirls In the Description text box, type Swirl shaped abstract images Click OK Figure 18 Album Properties dialog Step 3 Click and drag the images you think are swirl-shaped on to the Swirls album entry in the Albums list of the Library panel. Note that the images are not physically moved; they are just added to the album. Step 4 Click on the Swirls album in the Library panel. All of the images that you added to the album will be displayed in the main part of the Picasa window. 53 OUCS

62 DPIF/1 Digital images: a workshop Task 4 Investigate the slide show option Task 5 Explore the tags panel Look above the image thumbnails and identify the Play Fullscreen Slideshow button. Click on the button. The show will advance automatically. You can control the show using the left and right arrow keys Press ESC to stop a show and return to Picasa In the Libraries panel at the left of the Picasa window, select the Martin Heigan folder. The images in the folder will be displayed in the main panel. Use View Tags to display the Picasa Tags panel at the right of the Picasa window (Figure 19). Notice that these images are already tagged. Figure 19 The Picasa Tags panel OUCS 54

63 Digital images: a workshop DPIF/1 Step 3 Click on the Dietmar Teijgeman-Hansen folder. In the text box at the top of the panel type abstract and click +. This adds the tag to all of the images in the folder. Step 4 Click on the image that looks a little like a flower and a butterfly: Step 5 In the text box at the top of the Tag panel, type: flower and click +. Step 6 In the text box at the top of the Tag panel, type: butterfly and click +. Step 7 Close the Tag panel by clicking on its Close button. Task 6 Search for tagged images Identify the search text box at the top right of the Picasa panel. In the search text box, type flower Notice that as you type, Picasa dynamically searches all of the images (names and tags), updating the results in the main panel as you type. Leave a space after the word flower and then type butterfly You should see only the image that has both tags. Step 3 Clear the search results by clicking on the Clear your search button at the right of the search box. 55 OUCS

64 DPIF/1 Digital images: a workshop Task 7 Export an image Click on an image of your choice. Click on the Export button at the bottom of the Picasa window. This will display the Export to Folder dialog (Figure 20). Figure 20 The Export to Folder dialog Click on the Browse button and choose the Desktop as a location. Give the name for the exported folder to be Export Set the image size to 800 pixels. Select Custom (85) from the Image quality drop down menu. You should be familiar with the concepts of resolution and JPEG image from previous exercises. Step 3 Put a tick in the Add watermark tick box. Type: images workshop Click on Export. Task 8 Close Picasa Use File Exit to close Picasa OUCS 56

65 Digital images: a workshop DPIF/1 Find the exported image in the Export folder on the desk top. Double-click on the image to view it. Close the image viewer Using images in your work Images are a vital tool in communicating your research both in presentations and in print. It is often tempting, when deadlines loom, to use one of two approaches: Use a web search tool to find a suitable image, and then save the image to a folder on your computer for insertion into the document. Find an image in an existing document and copy and paste into the new one Using web sourced images The key issues here are copyright and quality. Copyright has been covered in an earlier section, but just to emphasise the point: images found on the web are more often than not subject to copyright. You should take care that you do not infringe that copyright by your use of the image. The quality of images on the web is often dictated by the need to make them quick to download and display in a browser; they will usually have been optimised to have a reduced file size at the expense of quality and detail. The best indication of the quality of an image is usually the pixel count, and some rules of thumb are given below as to how to judge whether the image will be suitable to use in your document at the physical size you need it Using images from other documents Most commonly used document producing software (Word, Pages, PowerPoint, KeyNote, etc.) have their own methods for optimising quality against file size. Sometimes this optimisation is hidden from you, and you may not even know that it has been done. This optimisation process is usually very efficient. Having placed the image in the document and sized it appropriately for the slide or page, you are unlikely to see any visible change to the image when the document is saved (at which point the optimisation occurs) and reopened. However, the pixel count will have been reduced. At a later date, should you need to reuse the image in another document, you may be tempted to simply copy and paste it. This will work, but only if you keep the image at the same size as it was in the source document. Should you try and enlarge it, you are likely to find that there is a noticeable degradation in the quality of the image. The lesson here is: when you obtain an image that you want to use, always keep the original and always return to the original each time you want to reuse that image. Image cataloguing software, such as Picasa (described above), makes the management of your image collections, in particular searching for tagged images, very easy. 57 OUCS

66 DPIF/1 Digital images: a workshop Discovering an image s pixel count Most image editors will have an option for displaying image information, including the number of pixels. Other options for finding this information are: In Windows: Open up your My Documents folder Navigate to the folder containing the image Hover your mouse cursor over the image file A pop-up should appear, giving the pixel dimensions of the image In Mac OSX Use Finder to locate the image in its folder CTRL + click on the file From the pop-up menu, select Get Info In the More Info section, you will find the image dimensions Using images in presentation tools A good rule of thumb, at least for PowerPoint, is that you should aim for about 150 dots for each inch of image on a slide (or 60 dots per cm). The measurements we are interested in are those given in the design view of the software; a standard PowerPoint slide is about 25cm (w) x 19cm (h), so to fill a slide, at good resolution, an image should be: 25 cm x 60 dots per cm = 1500 dots wide, and 19 cm x 60dots per cm = 1140 dots high So, the calculation you should make is: obtain the number of pixels in the image (see above), and then divide by 150 dpi (60 dpcm). This will give you an upper limit to the size of the image on the slide. You may get away with fewer dots depending on the image, and your view of acceptable image quality it is a rule of thumb after all. Be aware, that many presentation tools will optimise your images without asking! When you save your presentation, the software will examine your image resolution, the size you have made it on the slide, and then reduce the number of dots to 150 per inch (60 per cm). This will not noticeably affect the image quality, and could greatly reduce the size of the presentation file. However, if you subsequently want to make the image substantially bigger on the slide, you may see a loss of quality. Always keep a copy of the original image so that you can reinsert it at its original quality! There are some presentation tools, such as ARTstore s OIV (Offline image viewer) which are designed to present high quality images on screen. These applications do not optimise your images, but it is still wise to keep copies of the originals Using images in word processed documents Print requires higher pixel counts than on screen display. The rule of thumb for everyday quality is 200 dots per inch (or 80 dots per cm). For high quality printing, such as conference posters, you should aim for 300 dpi (or 120 dots per cm). The calculation you should make is: obtain the number of pixels in the image (see above), and then divide by the resolution you want dpi (80 dpcm) for normal quality, 300 dpi (120 dpcm) for high quality. This will give you an upper limit to the size of the image on the paper. OUCS 58

67 Digital images: a workshop DPIF/1 Many word-processors will optimise images in a similar way to PowerPoint. When you save the document the image quality will be reduced to a default number of dots per inch (usually 200) and so if you have made your image smaller on the page, you are likely to lose dots. This will not be noticeable, and has the advantage of reducing the document file size. However, if you then decide to make the image larger on the page, you may see a loss of quality. Always keep a copy of the original image so that you can reinsert it at its original quality! Professional desk top publishing tools such as InDesign do not optimise your images by default. 59 OUCS

68 DPIF/1 Digital images: a workshop Exercise 8 Using images in PowerPoint and in ARTstor OIV This exercise briefly shows the use of images in PowerPoint and OIV. It illustrates a particular strength of each tool: animation in PowerPoint image zoom in OIV There is much to else to learn about the tools and you should attend the relevant courses given at OUCS. Open PowerPoint Insert an image into a slide Save the presentation Insert and colour a copy of the image Crop the image Repeat for a second copy of the image Add a custom animation to the cropped images Save and view the slide show Open OIV Create a zoomable slide from a high quality image Save and preview the slide in OIV Task 1 Open PowerPoint Click on the Start button at the bottom right of the screen. Click on All Programs. Click on the entry for Microsoft Office. Click on the PowerPoint 2007 icon. Task 2 Insert an image into a slide Click on the Home tab in the ribbon. In the Slides category, click on the Layout button. Click on the Blank layout. If you do not have a set of guide lines crossing in the centre of the slide: In the Drawing category, click on the Arrange button. Select Align Grid settings to display the Grid and Guides dialog. Put a tick in the Display drawing guide in screen tick box. Click OK. OUCS 60

69 Digital images: a workshop DPIF/1 Step 3 Click on the Insert tab in the ribbon. Click on the Picture button Insert Picture dialog. to display the Select the HighResolution.tiff image from the Session Files folder and click Insert. The image will be inserted and fill the screen. Task 3 Save the presentation Task 4 Insert and colour a copy of the image Click on the Office button PowerPoint window. Select Save. at the top left of the In the Save As dialog, save the presentation as ImageAnimation.pptx on the Desktop. Click on the Home tab in the ribbon. In the Clipboard category, click on the Copy button. In the Clipboard category, click on the Paste button. A copy of the image will be overlaid on the original, but offset slightly. Step 3 Click and drag on the image to align it in the centre of the slide (completely covering the original). The guides should help you with the alignment. Step 4 With the image selected, click on the Format tab in the ribbon. In the Adjust category, click on the Recolor button. Select a Dark Blue variation. The image will be recolored. 61 OUCS

70 DPIF/1 Digital images: a workshop Task 5 Crop the image With the image selected, click on the Format tab. In the Size category, click on the Crop button. The selection markers around the image will change to crop markers (black bars). Task 6 Repeat for a second copy of the image Task 7 Add a custom animation to the cropped images Click and drag the middle left crop marker as far as the centre guide. Only half the image will be visible, with the original showing through from underneath. Click on the Crop button to turn off the crop marks. Click on an exposed area of the coloured image to select it. Click on the Home tab in the ribbon. Use Copy and Paste to get another copy of the original image. Align this second copy to the middle of the slide, hiding the two existing images. Click on the Format tab in the ribbon, and Recolor the image, as you did for the previous copy, but this time use a Dark Red variation. Step 3 Crop the image as you did for the previous copy, but do so from the right hand side. Click on the Crop button to deselect it. Click on the left (dark red) image. Click on the Animations tab in the ribbon. In the Animation category, click on the Custom Animation button. This will display the Custom Animation panel at the right of the PowerPoint window. Step 3 In the Custom Animation panel, click on the Add Effect. button. Choose Entrance More Effects. In the Add Entrance Effect dialog, click on Fade. Click OK. OUCS 62

71 Digital images: a workshop DPIF/1 Step 4 Click on the right (dark blue) image to select it. Step 5 Add a fade effect to this image as you did for the dark red image. Task 8 Save and view the slide show Click on the Office button at the top left of the PowerPoint window. Select Save. In the ribbon, click on the Slide Show tab. In the Start Slide Show category, click on the From Beginning button. Advance the animation by using the SPACEBAR or RIGHT ARROW key or mouse click. Step 3 Press ESC to return to PowerPoint. Click on the Office button and select Close to close PowerPoint. Task 9 Open ARTstor OIV Task 10 Create a zoomable slide from a high quality image Click on the Start button at the bottom right of the screen. Click on All Programs. Click on the entry for ARTstor OIV. In the OIV Getting Started dialog, select the option to Create a new presentation from my own images Click OK. In the Select image file(s) dialog, go to the Session Files folder and select the HighResolution.tiff image file. Click Add. Step 3 Click on the HighResolution image in the Image Palette of the OIV window (Figure 21) 63 OUCS

72 DPIF/1 Digital images: a workshop Step 4 Click on the Create slides from the selected image(s) button (circled in Figure 21). Figure 21 The OIV window Step 5 In the Add a slide to this presentation dialog, select the template for two side-by-side zoomable windows (Figure 22) Click OK. Figure 22 The OIV slide template selection dialog OUCS 64

73 Digital images: a workshop DPIF/1 Task 11 Save and preview the slide in OIV Step 6 The selected image is inserted on only one of the slides. Click and drag the HighResolution image from the Image palette to the unoccupied area of the slide. Use File Save to display the Save presentation dialog. Give the filename as: ZoomablePresentation Click Save. In the Slide Sorter panel, click on the View slide presentation button. Step 3 When the slide is displayed, a list of the control keys will be shown. The main keys are given below, so press ESC. Step 4 Use the following keys to interact with the slide: TAB Change the focus to the next zoomable image = Zoomin - Zoom out 0 Fit to screen 9 Actual size SHIFT LEFT ARROW SHIFT RIGHT ARROW SHIFT UP ARROW SHIFTDOWN ARROW Move image left Move image right Move image up Move image down Esc Exit the presentation Step 5 Press ESC to exit the presentation. Use File Exit to close OIV Keeping your images safe Your images may or may not be commercially valuable, but they certainly represent a significant investment of your time. Many of them will be of sentimental value, some of them may be important to your research, studies, or hobbies; the majority of them will be irreplaceable. There are two issues to preserving digital images: preservation of the data, and preservation of a readable data format. 65 OUCS

74 DPIF/1 Digital images: a workshop Preservation of the data You must firstly make sure that the image files are fully backed up, that is you have copies in more than one place. The web-based software discussed above has a distinct advantage here in that your images are stored on the servers made available by the service providers. We would hope and expect that they have procedures for backing up data they hold. However, these services are operated commercially, and there is the potential that the provider might go out of business, merge with another company, and/or perhaps change their conditions of service. It would be wise to consider having your own personal backup. Your images will invariably be held on a hard drive, often inside your computer, but perhaps housed in a separate external box. Hard drives are generally reliable, but they will eventually fail, either directly or through some failure of a supporting component. You can protect against this by having copies of your images on a second hard drive. This should ideally be completely separate to the hard drive that you use to store your originals; most likely it is an external hard drive. Ideally you will store this backup hard drive in a separate location. You might also consider copying your images to either a CD or a DVD. Digital image files are becoming larger with the ready availability of higher resolution cameras, and so DVDs are the most useful of the two, being able to store between 4 GB and 8GB of data. CDs and DVDs are regarded as having a lifetime of several years provided they are stored in a cool, dark, dry environment. When writing data to either CD or DVD, always verify that the write has been successful, and be careful when labelling them some inks and labels can damage the recording layer that is actually deposited on the top surface (the under surface is a clear protective layer). Consider storing your storage disks at a remote location, perhaps with a friend or relative. Many professional photographers adhere to the rule: 3 copies of each image, on 2 different types of media, and at least 1 copy held off-site Preservation of the format Long term preservation of the image data is important, but we must also consider the format of the image data. Common formats today are TIFF, JPEG and RAW. TIFF and RAW exist in a number of variants. JPEG is generally more universal. Most (non-professional) cameras default to the JPEG format, with the quality of the image being determined by the selection of image resolution (pixels wide x pixels high) and compression factor, through the camera s menu system. However, the RAW format (see earlier) is becoming more common. The RAW format typifies the problem. There is no agreed RAW standard (although one, DNG or Digital NeGative, is proposed), and so we are reliant on the camera manufacturer providing details of the format and possibly supporting software. OUCS 66

75 Digital images: a workshop DPIF/1 It may happen that in the future a particular RAW format is no longer supported by a manufacturer and potentially, after a few years, it may be difficult to find software that will read this older format. If we look far enough into the future, this could happen even with more widely accepted formats, such as JPEG. There is currently no solution to this, other than ensuring that our images (particularly critical images), are always stored in a current, generally available, format. This might entail revisiting our image backup every few years and rewriting the data in a different format. Of course this would have the additional benefit of ensuring that older backups do not degenerate and become unreadable Ingestion and backup of images - a scenario The individual elements of the process of getting images onto your computer (ingestion) and looking after them long term (back up) are. However, it can be difficult to devise a workflow that reliably helps you put them into practice. The following is one possible scenario. It is one that suits this author and it works well for him in his circumstances. It may not suit you, but it might be a starting point for you to adapt. The ingestion and backup process is illustrated in the flow diagram below(figure 23). You should read the following in conjunction with the diagram. Figure 23 Ingestion and backup process 67 OUCS

76 DPIF/1 Digital images: a workshop The media card from the camera is placed in a card reader. The use of proprietary software from camera manufacturers is avoided, to give more control over the process. Using the standard features on the operating system (for example Windows Explorer or Mac OS X Finder) the images are copied to a newly created temporary folder. The next step is optional, and depends on your view of the DNG format. This author considers the DNG format to be more viable in the long term than his standard camera format and so he converts the images to the DNG format. Adobe s free DNG conversion tool can be downloaded for Windows or Mac OSX from their website. Check that the copy/conversion process(es) worked. By default, the DNG format is not natively recognised by all operating systems. The author uses a copy of the Picasa Image Viewer (downloadable from Google) on Windows or Preview on Mac OS X to check the images are not corrupted. If the images are not viewable, then some investigation is needed. For example, are the images on the media card directly viewable? The DNGs are copied to a suitable folder in the folder structure used to store imported images (see discussion below). The author is happy to use only DNGs. Others may prefer to keep both DNGs and the original format. If you are not using DNGs then clearly you must copy the originals. The temporary ingestion folder is deleted. The images are copied to the image backup system (see discussion below). The author also updates his collection of backups on DVDs. Another visual check is made to ensure that images have not been corrupted in the backup process. If the images are not viewable, then some investigation is needed BEFORE erasing the media card. The media card is erased for reuse. Image correction and manipulation can now be started, with derivatives of the original images being backed up routinely. The author uses an editing application (Aperture for Mac OSX) which does not make changes to original images and stores only the alterations to be applied - however, these alterations still need to be backed up. In terms of the physical arrangement of backup devices, there are many different solutions. The diagram below (Figure 24) shows one particular solution that has worked for this author. It is based on a diagram in Peter Krogh s The DAM Book: Digital Asset management for Photographers. OUCS 68

77 Digital images: a workshop DPIF/1 Figure 24 Backup regime Images are copied on to the local hard drive (see above ingestion process). These images are also copied to a folder structure (see below) that acts as an archive of the original images. This archive sits on an external hard drive. This is an additive process, with new folders being created as repositories for the new original images. Changes to images are made in work files on the local (internal) hard drive. In the authors case this is using an image management application that does not make changes to image files. It records the image operations required to create derivative images from originals when needed. The working files are routinely copied to the local external hard drive (typically after each work session) Important system data is also routinely backed up to the local external drive. These might be application parameters, licence keys, etc. When required derivative images are created (perhaps for inclusion in documents or web pages). These are also routinely backed up to the external hard drive. In the author s case there are very few of these; derivatives are reproduced on demand through the image 69 OUCS

78 DPIF/1 Digital images: a workshop management application. In such a case it is the image management application s database that is backed up. Periodically, typically monthly, sometimes weekly, a second external drive is attached and the system data and working files are refreshed (mirrored) from the local external drive. At the same time, any new images and derivatives are copied over. The offsite hard drive is then disconnected and stored elsewhere. Again, periodically, the optical disk backup is updated by writing the new images and derivatives to DVDs (see below). There are a number of utilities available for helping with the synchronisation of files between locations (external hard drives, DVDs, etc.). These should be used with care and understanding. It is probably unwise to use any tool that creates backups and archives using its own proprietary format. Little has been said about the actual organisation of the images on the hard drives and DVD backups. Again there are many systems that could be used. The one described here (see diagram below) works well for the author, but should be adapted to suit your work preferences. Figure 25 Example folder structure OUCS 70