Search engines like accessible websites. An accessible website is text (or content) based. Search engines only read text. Accessible websites are more likely to be listed favorably with search engines because they provide more content, which makes them appear more relevant.

You can improve website efficiency through satisfying accessibility standards. Websites are easier to maintain by staff and are generally loaded faster by web browsers.

Most businesses stress their commitment to enriching their community. An accessible website is an example of such a commitment.

With anti-discrimination laws on books, an accessible website can help public institutions like university, municipalities, and other publicly operated entity avoid legal issues as it is required to cater to needs of all individuals.

These are but a taste of benefits an accessible website can offer your business. For more details, visit: http://www.w3.org/WAI/bcase/benefits.html.

Conclusion

To minimize file size of palette-based image formats like GIF and PNG, minimize their bit-depth, or number of colors. Each time you pass a power of two, file size jumps higher. By minimizing number of colors, and maximizing flat-color areas you will create smaller, more efficient images destined for Web.

Further Reading:

LZW Data Compression http://www.dogma.net/markn/articles/lzw/lzw.htm Mark Nelson breaks down LZW compression algorithm for Dr. Dobb's Journal of October 1989.

Multimedia: Use Lossy Compression for Smaller GIFs and PNGs http://www.websiteoptimization.com/speed weak/lossy/ Lossy compression lets you squeeze more bytes out of your GIFs and PNGs. Lossy compression increases identical pixel patterns to improve compression in indexed-color images.

Multimedia: Use Weighted Optimization http://www.websiteoptimization.com/speed weak/weighted/ Weighted optimization or regional compression applies different degrees of compression to different areas of your image. By varying quality within images you can improve file size.

Optimizing Web Graphics http://www.websiteoptimization.com/speed/12/ Chapter summary from Speed Up Your Site, shows how to correct, optimize, and compress images for minimum file size and maximum quality.

PNG Home Site http://www.libpng.org/pub/png/ Greg Roelofs site devoted to all things PNG.