Chapter 6 Images Learning Objectives This lesson looks at images and shows the students what they need to create and edit them. At the end of the lesson, the students will be able to: Discuss the various factors that apply to the use of images in multimedia. Describe the capabilities and limitations of bitmap images. Describe the capabilities and limitations of vector images. Define various aspects of 3D modeling. Describe the use of colors and palettes in multimedia. Cite the various file types used in multimedia. Estimated Time for Module: 1 hour, 30 minutes Few aspects of a multimedia project are as important as quality images. Before a designer can begin to create and prepare images for use in a multimedia project, an understanding of the fundamentals of computer images, color, and formats is crucial. This lesson shows the students how to prepare for the image creation process, how images are created and modified on a computer, how color is managed on computers, and what file formats are most commonly used. Preparing for Class Ideally, this class should be conducted in a computer lab with multimedia authoring software installed. Exercises in the lesson assume that the students have access to computers with image editing software as well as applications that include clip art collections. Review the exercises carefully before class and tailor them to the software that is available in the classroom. The project at the end of the lesson assumes that image editing software, such as Photoshop, is available. 000-2 6-1
Prerequisites for Class Before coming to class, the students should: Have read Chapter 6 in their textbooks. Be familiar with all previous material. Class Preparation Notes PowerPoint slides to accompany the lesson plan can be found on the CD. You will also find the figures for Lesson 6 as JPEGs on the CD. General Teaching Tips This lesson looks at image fundamentals in computers. To achieve the primary objectives: Ensure that the students understand the differences between bitmap and vector graphics. Keep in mind during the discussion of color that much of the information about color perception and physics is academic. If time is short, focus on how computers handle colors. Cover image file formats briefly if time is short. Key Terms additive primary color autotracing Bezier curves bitmap Cartesian coordinates clipboard Cyan, Magenta, Yellow, and Black (CMYK) 000-2 6-2
dithering dot pitch Drawing Interchange Format (DXF) extrude flare Graphics Image File (GIF) Initial Graphics Exchange Standard (IGS) Joint Photographic Experts Group (JPEG) lathe modeling morphing objects palette flashing pels PICT pixels properties quantum theory QuickTime VR (QTVR) real estate rendering Red, Green, and Blue (RGB) rotated scan rate 000-2 6-3
scenes shape subtractive primary color Tagged Image File (TIFF) vector Video Graphics Adapter (VGA) z dimension Lecture Outline Images are an important part of many multimedia presentations. This lesson shows how images are created and delivered on computers. I. Before You Start to Create Exercise Have the students open a graphics program and create a title page graphic for a project from scratch. Give no further instructions and give the students about five minutes to work. This exercise will illustrate the futility of sitting down at the computer to create graphics without first coming up with some sort of plan. A. Plan your approach. 1. Work out a graphic look for your project ahead of time. a) You can make a plan in your head. b) The group can brainstorm ideas in creative sessions. 2. Put ideas on paper. a) Outline the project and make a flowchart. b) Use note cards to simulate pages of the project. B. Organize your tools. 000-2 6-4
1. Is your authoring software able to create all the images and buttons that you need? a) If not, obtain and prepare additional software tools. b) You may want a specialized graphics program for serious graphics work. C. Multiple monitors. 1. Screen real estate is invaluable to the multimedia designer. Insider Information Another consideration for multimedia designers is the type of monitor they use. Flatpanel LCD monitors are becoming common on personal computers due to their low heat output, thin profile, and low power consumption. Many graphics professionals, however, still prefer traditional cathode ray tube (CRT) monitors. Colors on a CRT monitor are considered to be more natural, and the curved shape of a CRT monitor means that glare is less of a problem than with some flat panel monitors. II. Making Still Images Discussion Point It is important to remember that still images serve a huge variety of purposes on computers and in multimedia projects. Have the students list some possible uses for stills in their projects. Try to get some less obvious examples, such as buttons and icons. A. Still image basics. 1. Still images are drawn on computers in one of two ways. a) Bitmaps (1) A simple matrix or grid of dots and color information. (2) The smallest element of a bitmap is a pixel. b) Vector-drawn graphics. (1) Vector graphics are described as mathematical formulas. 000-2 6-5
(2) CAD and 3-D animation programs often use vector graphics. 2. Images are usually compressed to save space. a) Formats such as GIF, JPEG, and PNG incorporate compression. B. Bitmaps. 1. Clip art. a) Clip art suppliers can provide ready-made graphics. b) Many applications come with bundled clip art. Exercise Instruct the students to launch a program on their computers (such as Microsoft Word) that includes clip art. Have the students open the clip art collection in the program and browse the available images. In Word, for example, click Insert Picture Clip Art. c) Licensing restrictions vary widely, so check carefully when using clip art. (1) Don t assume that all clip art is provided with an unlimited use license. 2. Bitmap software. a) Many programs can create and edit bitmaps, including the following. (1) Dedicated graphics programs such as Photoshop. (2) Many multimedia authoring tools such as Director. (3) Simple painting tools such as Microsoft Paint. (4) Some office productivity software such as Word. Exercise Instruct the students to launch an image editing program on their computers. Determine which programs are available before class and provide specific instructions on opening the program and drawing a simple shape. A dedicated image 000-2 6-6
editor such as Photoshop is best, although programs such as Paint, Director, or Word will suffice. Keep this exercise short, as many students are probably already familiar with image editors. 3. Capturing and editing images. a) Images of your computer screen can be easily captured. (1) On a Macintosh, press COMMAND-SHIFT-3 to generate a PICT2- format file named Picture in the root directory. (2) In Windows, press PRINT SCREEN to copy a screen shot of the entire desktop to the clipboard. Press ALT-PRINT SCREEN to copy only the active window on the desktop. b) Screen capture software simplifies various tasks and provides more options. Teaching Tip To grab a region of the screen unrelated to a full screen or window, use a demo version of SnagIt from www.techsmith.com (Windows). 4. Scanning images. a) Almost any object can be scanned using a scanner and image-editing software. b) Artists may find that it is easier to paint or create on a traditional canvas, and then scan the work into the computer. C. Vector drawing. 1. How vector drawing works. a) Vector graphics are defined using formulas rather than bitmaps. b) The following formula will draw a rectangle with a red border and blue fill in the upper-left corner of the screen: RECT 0,0,200,200,RED,BLUE 000-2 6-7
2. Vector-drawn objects versus bitmaps. a) Vector graphics are more easily scaled. b) Vector graphic files are usually much smaller in size than bitmap files. (1) This makes vector graphics Web-friendly. c) If many vector graphics are displayed at once, screen refresh may slow due to calculation time. (1) For this reason, bitmaps are better suited for large images with many different colors (such as photographs). d) Bitmaps usually cannot easily be converted to vector. e) Vector graphics require a plug-in to work in Web browsers. D. 3-D drawing and rendering. 1. Many users have come to expect 3-D art in commercial multimedia. 2. Special software can help you draw 3-D art on a 2-D surface with features such as: a) Directional lighting. b) Motion. c) Different perspectives. 3. 3D creation tools include the following. a) Carrara Studio, an upgrade from Ray Dream Designer. b) Caligari True Space, multiple versions. c) Form*Z. 4. The depth of a 3-D object is calculated as the z dimension. 5. A 3-D object may contain such elements as blocks, cylinders, cones, and so on. Exercise 000-2 6-8
Instruct the students to launch Microsoft Excel. Enter two columns of six integers each say years and sales numbers. Choose Chart Wizard / Surface and then select a 3-D chart. Students may go right to Finish so that a 3-D chart is shown. Click on the chart (not the frame the chart is shown in). When the corners of the chart show handles, dragging one of those handles will allow a student to rotate the chart and view it from any angle. Teaching Tip Figure 6-11 on page 137 of the textbook illustrates how various elements make up a single 3-D object, in this case a chair. a) Objects and elements in 3-D space have properties such as color, texture, location, and so on. b) Objects are created by modeling them in a 3-D application. (1) Objects are modeled using shapes, which you can create or import. (2) Shapes can be extruded or lathed. Teaching Tip Figure 6-12 on page 137 of the textbook illustrates extruding and lathing of 3-D shapes. 6. A 3-D scene consists of various objects. a) Objects are arranged in a 3-D space. b) Lighting and camera views can be configured. c) Shading can be used to provide a variety of effects. (1) Flat shading is fastest for a computer to render. (2) Gourand shading, Phong shading, and ray tracing take longer to render, but are more realistic. Teaching Tip 000-2 6-9
Figure 6-13 on page 138 of the textbook illustrates various types of shading for 3-D scenes. 7. When the modeling is complete, the final output must be rendered. a) The computer uses algorithms to apply effects and build the final output. b) Rendering can be a time-consuming and processor-intensive process. E. Panoramas. 1. QuickTime VR allows you to view a single surrounding image. 2. Several overlapping images may be stitched together to create a single panoramic view. Teaching Tip Students experienced a QuickTime VR panoramic presentation during the project at the end of Lesson 1. III. Color A. Understanding natural light and color. 1. Quantum theory. a) Light passes through atoms, each of which produces a unique color. (1) Max Planck developed this theory. b) Light comes in a form of energy called photons, or quanta. (1) Niels Bohr developed this theory. 2. Color is the frequency of a light wave. a) The rainbow shows the range of perceptible colors. (1) Colors below that range are in the infrared range. (2) Colors above that range are in the ultraviolet range. b) The color white is actually a mix of all the color frequencies. 000-2 6-10
3. Human eyes perceive colors with a wavelength of 400 600 nanometers. a) Light rays stimulate rods and cones in the eye s retina. b) Receptors are sensitive to millions of combinations of red, green, and blue light. c) Color perception is further influenced by cultural meanings and associations of certain colors. Discussion Point Have the students describe what certain colors mean to them. For example, what does the color white symbolize or suggest? In many Western cultures, white symbolizes purity or innocence, whereas in Eastern cultures (such as China or Japan), white is associated with funerals. B. Computerized color. 1. Monitors and color. a) Computers generate color using combinations of red, green, and blue (RGB) light. (1) 8-bit color offers 256 possible color choices. (2) 24-bit color offers 16,777,216 possible color choices. (3) Broadcast TV uses a different color model called YUV. Insider Information The YUV color system defines color using one luminance signal (Y) and two color difference signals. The U portion of the signal carries blue minus luminance (Y) data, and the V signal carries red minus luminance (Y). Video will be covered in greater detail in Lesson 8. b) Remember that a computer monitor is a source of light. (1) Printers make color using the subtractive colors cyan, magenta, yellow, and black (CMYK). 000-2 6-11
Teaching Tip The table on page 143 of the textbook lists perceived colors from various combinations of RGB color. c) VGA computer monitors display, at a minimum, 8-bit color at 640 by 480 pixels. (1) Most monitors currently display more colors at higher resolution, although sticking to 640 by 480 will ensure the widest audience. C. Color palettes. Teaching Tip Figure 6-16 on page 146 in the textbook shows a variety of color palettes. The table on page 145 lists the number of colors available in a palette at various color bit depths. 1. A palette is a mathematical table that defines colors. a) A palette is also called a color lookup table (CLUT) on Macintosh. b) The standard color palettes on a Macintosh and in Windows differ slightly. (1) This is one of the reasons that the colors of an image appear differently on Macintosh and Windows systems. (2) 216 colors of the standard 256 color palettes are common to both computer systems. 2. About palette flashing. a) If you change the color mapping of your 256 color palette, screen flashing may occur. b) To avoid palette flashing: (1) Work from a single palette of 256 colors shared by all images. (2) Fade each image to white or black before showing the next image. 000-2 6-12
3. Dithering. a) Dithering is where colors that aren t in the current palette are converted (or dithered) to the nearest color. b) If you are not happy with the color dithering result of an image, try converting it to grayscale. Teaching Tip Figure 6-17 on page 148 in the textbook illustrates dithering. IV. Image File Formats A. Macintosh formats. 1. Apple developed the PICT format as a way to accommodate bitmaps and vector graphics. B. Windows formats. 1. Bitmaps (BMP) have long been a common Windows graphics format. 2. Other common bitmapped formats include the following. a) PCX b) TIFF c) JPEG d) GIF e) PNG C. Cross-platform formats. 1. Virtually all bitmap graphics are currently cross-platform compatible. Discussion Point Of all the formats available, which are often the safest to use today? Why? Most students will probably agree that a Web-friendly format such as JPEG or GIF is the safest choice, not only because they are supported on a wide variety of systems, but also because they incorporate compression that many other formats do not. For 000-2 6-13
examples of these two Web-friendly formats, the students can visit google.com and click on the images tab. It will search for images by keyword such as puppies. 2. For vector drawn graphics, cross-platform formats include the following. a) DXF (1) Developed by AutoDesk as an ASCII-based drawing interchange file for AutoCAD. b) IGS (1) Short for IGES, or Initial Graphics Exchange Standard. (2) Developed as an industry standard exchange format for CAD drawings. Project You have been provided with a TIFF file that consists of four versions of a 3-D object. Open this file in an image editing program. Once open, save four separate, uniquely named copies of the file. Next, change the color palette used in each of the files. Use the following palettes: Macintosh system palette. Windows system palette. Web (216 color) palette. Grayscale. Project Solution Provide each student with a copy of the figure file for Figure 6-14 in the textbook. This file, F6-14.jpg, can be found on the CD that accompanies this book. If time is short, provide specific instructions for changing the color palette in the available graphics software. For example, if the students have access to Photoshop or Canvas, they would adjust the palettes using the Image Mode Indexed Color menu. Review completed files for proper application of palettes. During review, draw attention to the effects that 000-2 6-14
different color palettes can have on a single image. In Director, use the Modify Transform Bitmap command. If the students are using Director, only Macintosh and Windows system palettes are available. However, you can modify the project so that they use palettes with varying bit depth. Chapter Review This lesson looked at images and showed the students what they need to create and edit them. Objectives included: Discussing the various factors that apply to the use of images in multimedia. Describing the capabilities and limitations of bitmap images. Describing the capabilities and limitations of vector images. Defining various aspects of 3D modeling. Describing the use of colors and palettes in multimedia. Citing the various file types used in multimedia. Assessment Quiz Produce a handout and have the students answer the following questions. Questions 1. What are the two ways to outline the graphic presentation of your project? 2. What is the best way to increase screen real estate? 3. What are the two types (not file formats) of still images on a computer? 4. Which method mentioned in Question 3 is best for photo-realistic images? 5. Which method mentioned in Question 3 usually produces smaller file sizes? 6. What are the two methods for creating 3-D shapes from 2-D drawings? 7. List three different kinds of programs that usually offer image editing. 8. What kind of light is above the spectrum of perceptible light to the human eye? 000-2 6-15
9. Fill in the blank: The process of converting unavailable colors to the next nearest color is called. 10. Fill in the blank: A single picture element is called a. 11. Fill in the blank: The depth of a 3-D image is also called the dimension. 12. Fill in the blank: A 3-D may be made up of many elements such as blocks, cylinders, and cones. 13. True or false? Clip art collections offer collections of unlimited-use art for your projects. 14. True or false? A picture of the computer screen can be captured without any special capture software. 15. True or false? Artists may find that it is easier to paint a picture on a canvas, and then scan it into the computer. Answers 1. The ways in which you can outline the graphic presentation of your project include creating a flowchart, using index cards, or creating a storyboard. 2. The best way to increase screen real estate is to use multiple monitors. 3. The two types of still images on a computer are bitmaps and vector drawings. 4. Bitmapping is best for photo-realistic images. 5. Vector graphics usually produce smaller file sizes than bitmaps. 6. Two methods for creating 3-D shapes from 2-D drawings are extruding and lathing. 7. Programs that usually offer image editing include multimedia authoring tools, office productivity applications, painting tools, and dedicated image editors. 8. Ultraviolet light is above the spectrum of perceptible light to the human eye. 000-2 6-16
9. The process of converting unavailable colors to the next nearest color is called dithering. 10. A single picture element is called a pixel. 11. The depth in a 3-D image is also called the z dimension. 12. A 3-D object may be made up of many elements such as blocks, cylinders, and cones. 13. False. Clip art usually has some usage restrictions. 14. True. A picture of the computer screen can be captured without any special capture software. 15. True. Artists may find that it is easier to paint a picture on a canvas, and then scan it into the computer. 000-2 6-17