KSCC Colour Management

Transcription

1 Meetings held at: Sapphire Room Warilla Bowls & Recreation Club 1 st & 3 rd Wednesdays of the month 7:30pm KSCC Colour Management Colour management systems use profiles to help reconcile colour differences among devices, so that you can confidently predict the colour that you'll see when you share or print photos. Devices such as digital cameras, scanners, monitors, and printers. Each of these devices reproduces a different range of colours, called a colour gamut. As you move an image from your digital camera to your monitor, and finally to a printer, the image colours shift. Therefore, it's important to have a good Colour Management Workflow. Terms: srgb - the s stands for Standard. This is the universal colour used for monitors, tablets, phones, printers, and web etc. Most printing labs only take srgb. Gamut - is the term used to describe the range of colour values that fit in a colour space. Bicubic - This re-sampling method works by evaluating adjacent and nearby pixels, performing complex calculations on their values in order to predict what the pixel being worked on should be. 1. Screen Calibration: Having a properly calibrated screen is the first step in a good colour management workflow. Without it, you won't achieve in print, what you see on your screen. For this you need a Colorimeter such as a Spyder ($129 - $279) or Colour Munki. ($299 +) There is also the ColorHug by Hughski (approx $130) If you don't have a colorimeter you can try calibrating through Windows. (which doesn't guarantee good colour). Go to Windows Control Panel Colour Management - Advanced tab Calibrate Display. In Windows 7, go to Control Panel > Calibrate Display Colour. Run through the basic gamma, brightness and contrast settings. You'll then come to the screen where you remove the colour cast from the gray bars. When finished, print an image. Keep the image open on screen and adjust your monitor to match the print. It's not the ideal way to do it, but it may help. President: Vicki Luckins Ph: Po Box 45, Warilla NSW 2528 Mob: president@kscameraclub.org Web: Page 1 of 19

2 2. Setting Up Photoshop Changing some settings in the Photoshop preferences will improve Photoshop's performance. Choose Edit > Preferences and select General from the flyout menu. General: Colour Picker should be left at Adobe. Image Interpolation - can be left at either Bicubic Sharper or Bicubic Smoother, depending on what you do the most; reduce or enlarge your images Tick or un-tick the appropriate boxes in the Options section. The General Preferences dialog box. Making interface tweaks: Select Interface from the left menu. If you are using Photoshop on a laptop, turn off the Enable Gestures option. If you leave it on, you can accidentally rotate and zoom using your laptop's track-pad. Page 2 of 19

3 The Interface Preferences dialog box (CS6 above). Photoshop CC Interface has been broken up into three more tabs; Workspace, Tools and History Log. Leaving these settings at default is fine. If you don't like your images opening as Tabs, un-tick the box. Enhancing performance: Choose Performance from the left menu. This is where your set up your Ram and processor. Page 3 of 19

4 Needless to say, the more Ram you have, the faster Photoshop will process images. By default, Photoshop is set to use 70% of your available Ram, not your total Ram. It is almost impossible to run Photoshop at 100% Ram. If increasing the Ram, keep within the amounts suggested. History & Cache settings: The Cache Levels setting helps Photoshop redraw high-resolution images. It saves low-resolution versions of the image to update the image onscreen, live. If you are using large file sizes, you may want to consider moving your Cache Levels to 8. If you are using a lot of layers in smaller sized documents, you may want to reduce the Cache Levels setting. The Cache Tile Size setting is all about processing data. Photoshop processes data as tiles, and it likes to use larger tile sizes. Larger tile sizes make Photoshop faster when processing complex operations (such as dialog boxes that require you to click OK), but onscreen edits are slower with larger tiles. This can be changed, depending on what you're doing. If you don t know what you re doing, leave it at default. NB: The default setting for the Maximize PSD And PSB Compatibility now comes under "File Handling" Keep this option is at "Always", so it won't ask every time you save. Scratch Disk use to reside here, but now in Photoshop CC, it has its own tab. The scratch disk is your hard drive. Photoshop uses your hard drive as a temporary "swap" space, or virtual memory, when your system does not have enough RAM to perform an operation. If you only have one hard drive or partition in your computer, then the scratch disk will be the drive where your operating system is installed (the C drive on a Windows system). Refining cursor settings: Select Cursors from the left menu. Page 4 of 19

5 By default, the Painting Cursors setting is Normal Brush Tip. That means when you choose a 10- pixel hard brush, you see a 10-pixel circle, and it paints a 10-pixel stroke. If you soften the brush, it still appears as a 10-pixel hard-edge brush, but when you paint, there is a soft edge that you have to take into account. Instead, change your setting to Full Size Brush Tip, and Photoshop will show you the exact size of your brush, including the soft edge. NB: If you have ever lost your brush cursor it may be because you have the Caps Lock on. If turning it off doesn t get your brush back, you may want to close and re-open Photoshop, or even reboot the computer. Units and Rulers: Here you will be able to set if you want your ruler in Inches, Pixels, Centimeters etc. Set the Print Resolution to 300 ppi as this the optimal print setting. The Screen Resolution can be left at the default setting. However, to set it correctly for viewing images at Print Size in Photoshop, follow the steps below. Units and Rulers Page 5 of 19

6 Screen Resolution - Setting Correct View/Print Size: a. Create a blank document, 9 x 9 inch square, with has a resolution of 300 ppi, and dimensions. b. Fill it with white if it is not already filled c. From the menu choose View/Print Size d. With an accurate ruler and taking care not to damage your screen, measure the width of the image, in inches. It will most likely be smaller than 9 inches e. Divide 9 inches by the actual measurement you obtain from the screen measurement and this will give the correction factor. f. Next, go to Edit/Preferences/Units & Rulers and find the screen resolution. Most likely it is set at 72 pixels/inch g. Multiply this current ppi, (72), by the correction factor you just calculated, and enter the result in the screen resolution field. Click OK. The resulting screen resolution may have a decimal fraction so round it up to the next number. From now on, when you choose View/Print Size your screen will display the actual dimensions of the print. Optimizing your workspace: The Toolbar: After you have set your preferences, you can optimize your Photoshop workspace to speed up your workflow. The toolbar is set to one-column by default. Keeping it is set to the default saves space. However, it can be changed to a two-column toolbar by clicking the double arrow icon in the top left corner of the toolbar. Compacted to a two column format can help with headaches and eye strain after long exposure. One column can be visually tiring. The two-column format puts all the tools in one quadrant of the screen. Page 6 of 19

7 Palettes: Photoshop has a lot of options when it comes to panels and workspaces. Removing unused panels and saving your own workspace can really enhance your workflow in Photoshop. Go to Window in the menu at top of the screen. Tick or untick the palettes you want or don't want open on screen. Open palettes. Windows menu. Tick or un-tick palettes. Page 7 of 19

8 3. Working Colour Space: The coloured area in this image is an approximation of the visible light spectrum, or the gamut (or range) of colours, visible to the human eye. The triangles in the image, map out the colour spaces, or the gamut of colours spanned by the srgb and Adobe RGB colour spaces. The two most popular work spaces in Photoshop, are srgb and Adobe RGB. There's also ProPhoto RGB, which has its Pros and Cons. It's a much larger colour space than adobe, however there are colours that go outside the visible spectrum. Your monitor is not able to see the whole colour range available. Lightroom uses only ProPhotoRGB colour space, so if switching between the two programs it's probably best to keep Photoshop in ProPhoto. The recommended working colour space for Photoshop is Adobe RGB. It s a larger colour space than srgb, your camera, (if shooting jpg) most likely will be able to capture images in it, and your monitor can easily see it. However, if taking or sending your images out to a lab for printing, to be projected, or for the internet, don t forget after editing, to then convert to srgb before saving (as) your final version. If not, you will NOT get the colours you expect to see. Page 8 of 19

9 Saved with ProPhoto profile, viewed on projector with srgb working space. Photo by Bob Green Same Image converted to srgb profile, viewed on the same projector. Photo by Bob Green Page 9 of 19

10 Set up Photoshop's Working Colour Space To set up Photoshop's working colour space, go to Edit - Colour Settings. Select Adobe RGB as your working space. Set the Gray working space to Gray Gamma 2.2. since that value closely corresponds to the luminance response of human vision. Apple's ColorMatch space and ProPhoto, use a gamma of 1.8. however, images will appear too dark on more than 90% of monitors. Leave Dot Gain at 20%. This option is used more for Press Printing. Uses Adobe RGB as the RGB working space; the Grayscale working space is Dot Gain 20%. This option preserves embedded profiles and assigns Adobe RGB when opening untagged files. Un-tick "Desaturate Monitor Colours by" and "Blend RGB colours Using Gamma". Conversion Options: Engine - Choose Adobe (ACE) Intent - Perceptual or Relative Use Black Point Compensation - tick Use Dither (8 bit/channel images) - tick Compensate for Scene-referred Profiles - un-tick Page 10 of 19

11 4. Bit Depth 8 Bit or 16 Bit Images It s all to do with Maths. To keep it simple, an 8 bit image, gives a total of 16.8 million possible shades of colour to use. A 16-bit images, gives 281 trillion possible shades of colour. So obviously the more shades of colour you start out with in your image, the better. Excessive processing on 8 bit images can produce banding in areas such as skies, which can t be fixed. Therefore, begin working on your images in 16 bit. You will find that some filters in Photoshop won't work with 16 bit images, so you will need to convert to 8 bit after editing, to use them. (Make sure "Dithering 8 bit/channel" is ticked in the Colour Settings, to help prevent banding). 8 bit after sever processing - banding in the sky. 16 bit after sever processing - no banding Page 11 of 19

12 Greyscale 8 bit and 16 bit comparison 5. Adobe Camera Raw When you open a raw file in ACR, the bottom centre of the window (under the image) will have some settings you can change. Click on the blue text to open the settings dialogue. Page 12 of 19

13 Under the "Colour Space" section, there are now options for Printer Profiles as well as the standard Adobe, srgb, Colour Match and Pro Photo. Options in Photoshop CC. Earlier versions of Photoshop will look slightly different. "Bit Depth" should be 16 bit to take advantage of the larger colour gamut. "Under Image Sizing", choose the size and resolution you want your images to be. Once you've made your selections, hit "OK" and these settings will be kept for future use. 6. ICC Profiles: An ICC profile is a file that tell devices how to achieve accurate colour. All devices, whether cameras, monitors, or printers, each have their own ICC, or Colour, Profiles and therefore will reproduce the same colour, differently. Just the same as each person sees the same colour differently. These colours are called "Device Dependent Colours". Once you know the colour profile of the camera and the profile of the monitor, etc, the colour management engine in Photoshop, can translate the camera's profile to the monitor's profile to get accurate colour on the monitor. Page 13 of 19

14 7. Soft Proofing Before starting work on an image, you should Soft Proof it. This will give you a good representation of what your image will look like when printed. Each time you open your image you'll need to proof it again. Setting Up A Soft Proof a. Open your image. b. Go to View - Proof Setup Custom c. Under the Device To Simulate dropdown, choose the printer and combination paper you intend to use, if printing at home. If sending to a lab, or using for Projected Images, select Monitor RGB. Monitor RGB is the name given to the ICC profile when you calibrate your monitor. Some outside labs may supply an ICC profile for their printer that can be downloaded to add to this list. d. Do NOT tick "Preserve RGB numbers". In the "Rendering Intent" drop down, select Perceptual. Tick the "Black Point Compensation" check box and tick the "Simulate Paper Colour" check box. Click ok to use for this image only, or click "Save" to keep for future use with other images. Give it an appropriate name you'll remember. Preserve RGB numbers is mostly used in a CMYK workflow. Page 14 of 19

15 Turn On Gamut Warning: Turning on the "Gamut Warning" (under View) shows how Out of Gamut colours are going to be affected, meaning, what your monitor can produce but your printer can t. Proofed Image Proofed Image with Gamut Warning turned on. Under view, select "Gamut Warning". e. To correct the colour in the gamma warning, there are a few options: o adjusting levels or curves o using different paper type o using a hue/saturation adjustment layer to lower the saturation in the problem areas 8. Printing When printing, you need to make sure your settings reflect those you set up in Photoshop. After setting up Photoshop and adjusting your image, you don't want the printer to decide how your image will look. Printer Properties dialog for the Canon MG6200: a. Under the Colour Management area, "Colour Handling" should be set to "Photoshop Manages Colour". Select the "Printer Profile" that you used to Soft Proof in Photoshop. Page 15 of 19

16 b. Click on "Print Settings" to open the "Settings/Properties Dialogue" window. Colour Handling and Printer Profile c. Under the Main tab, choose the quality at which to print. Under the "Colour/Intensity" area, select "Manual", then "Set..." Printer Properties Page 16 of 19

17 In the next window that opens, Click the Matching Tab and set Colour Correction to "None". That will disable the printer driver colour correction, leaving Photoshop to do the job. Choose "None" under the "Matching Tab" 9. How to Deal With Rendering Intent ICC profiles usually contain four Rendering Intents. These define how the colour reproduction process should cope with colours and tones. The two options generally used for photography, are Perceptual and Relative Colorimetric. They both produce a slightly different rendering and there is no right answer as to which one to use. The best way to decide, is to soft proof the image in Photoshop with each intent, do a small test print and see which rendering you prefer. The same goes for using the Simulate Paper option. Page 17 of 19

18 Rendering Intent Perceptual Saturation Relative Absolute Use in Photography Sometimes known as 'Photographic', renders colours in a way which is natural to the human vision. Takes colours that are orbiting out of gamut and brings them in to gamut by squeezing them all in together and moving most colours around slightly. Perceptual should usually be used for colour transparencies, and often also gives the best results for scans from reflection colour prints. Pro - No banding. Unlike colours in the centre don t shift. Con - Slight colour shift. None. This will pull saturated colours out to the edge of the gamut, thereby increasing saturation, or colour 'strength'. It is intended to be used for vector graphics; i.e. logos, line-art, etc. Never use it for photographs (except special effects) or proofing! Takes colours that are out of gamut and maps them to in-gamut equivalent colours. Can be used for photos. Pro - Unlike colours in the centre don t shift. Con - Possible banding in areas such as skies. (re the gaps in the image) None (used for medical imaging) Rendering Intents define how the colour reproduction process should cope with colours and tones. Colours out of gamut Relative Perceptual Page 18 of 19

19 Ref: Jeff Lazell from Xrite on Youtube Datacolor Spyder Color Munki Adobe.com Digital Photography School Page 19 of 19