Sams Teach Yourself HTML 4 in 24 Hours

By Dick Oliver

• Table of Contents
  • Copyright
  • About the Author
  • Acknowledgments
  • Tell Us What You Think!
  • Put Your HTML Page Online Today
  • I. Your First Web Page
  • Hour 1. Understanding HTML and XML
  • Hour 2. Create a Web Page Right Now
  • Hour 3. Linking to Other Web Pages
  • Hour 4. Publishing Your HTML Pages
  • II. Web Page Text
  • Hour 5. Text Alignment and Lists
  • Hour 6. Text Formatting and Font Control
  • Hour 7. Email Links and Links Within a Page
  • Hour 8. Creating HTML Forms
  • III. Web Page Graphics
  • Hour 9. Creating Your Own Web Page Graphics
    • Choosing Graphics Software
    • Graphics Basics
    • Preparing Photographic Images
    • Controlling JPEG Compression
    • Creating Banners and Buttons
    • Reducing the Number of Colors
    • Interlaced GIFs and Progressive JPEGs
    • Summary
    • Q&A
    • Workshop
  • Hour 10. Putting Graphics on a Web Page
  • Hour 11. Custom Backgrounds and Colors
  • Hour 12. Creating Animated Graphics
  • IV. Web Page Design
  • Hour 13. Page Design and Layout
  • Hour 14. Graphical Links and Imagemaps
  • Hour 15. Advanced Layout with Tables
  • Hour 16. Using Style Sheets
  • V. Dynamic Web Pages
  • Hour 17. Embedding Multimedia in Web Pages
  • Hour 18. Interactive Pages with Applets and ActiveX
  • Hour 19. Web Page Scripting for Non-Programmers
  • Hour 20. Setting Pages in Motion with Dynamic HTML
  • VI. Building a Web Site
  • Hour 21. Multipage Layout with Frames
  • Hour 22. Organizing and Managing a Web Site
  • Hour 23. Helping People Find Your Web Pages
  • Hour 24. Planning for the Future of HTML
  • VII. Appendixes
  • A. Readers' Most Frequently Asked Questions
  • B. HTML Learning Resources on the Internet
  • C. Complete HTML 4 Quick Reference
  • D. HTML Character Entities

Reducing the Number of Colors

One of the most effective ways to reduce the download time for an image is to reduce the number of colors. This can drastically reduce the visual quality of some photographic images, but works great for most banners, buttons, and other icons.

In Paint Shop Pro, you can do this by selecting Colors, Decrease Color Depth. (Most other graphics programs have a similar option.) Choose 16 Colors (4-bit) when your image has very few colors in it. If the image has lots of colors (or the image doesn't look good when you try 16 Colors), select Colors, Decrease Color Depth, 256 Colors (8-bit) instead. The software will automatically find the best palette of 16 or 256 colors for approximating the full range of colors in the image.

When you reduce the number of colors in an image, you will see a dialog box with several choices (see Figure 9.9). For Web page images, you will almost always want to choose Optimized Octree and Nearest Color. Leave all the options on the right side of the dialog box unchecked; they will seldom improve the quality of an image noticeably.

Figure 9.9 Reducing the number of colors in an image can significantly decrease file size without dramatically changing the appearance of the image.

There is a special file format for images with a limited number of colors; it's called the Graphics Interchange Format (GIF). To save a GIF image in Paint Shop Pro, select File, Save As and choose CompuServe Graphics Interchange (*.gif) as the image type.

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