On Wed, 08 Nov 2000 15:29:17 +0000, Ron Clarke wrote: > Hi Clarence, >> From: "Clarence Verge" >> Zipped Bit Map. >> 100% lossless. >> Almost always smaller than just about any other image format. ^^^^^^ > I still think I missed something. I had guessed "zipped bitmap" and > thought I'd try it. Got a nice big (just over 1 MB) .BMP and zipped it > to .ZBM. > The zip was reduced to about 85 % of the original .BMP. :( > That is obviously not good enough, so what did I miss ? Quite obviously, if I had gotten a result like that I might have given up immediately. Zip compression (or any other kind) depends on patterns. Totally random binary patterns don't compress at all. MOST of the screen images we look at however, are very NON random. A randomly selected Arachne (640x480x8bit) screen (308,278 bytes) will zip to 7kb-14kb. On average, 10kb. That's about 3% of original. Big screens with a lot of detail (1024x768 shot of Mars) start at 768,510 bytes and zip to 266,182 bytes. But a GIF of the same screen is 305,978 bytes. So, while the compression isn't quite as good when there is a lot of random detail, it's still the best game in town. Plus, it will also load faster than the gif. To see the above, goto: http://www.hwcn.org/~ao773/myfiles/images/1024x768/ I personally don't bother zipping Hicolor or TruColor images. While zipping will still represent the best lossless storage or transmission method, I would (personally) take an initial factor of 2 (Hicolor) or 3 (TruColor) by changing my video mode to 256 colors before BMPing.<g> Another point worth thinking about: It just took Arachne 54 sec to download and display home.arachne.cz. It only took Arachne 23 sec to download and display an IMAGE of the above. And that was the COMPLETE virtual page, not just the first of 4 or 5 screens. What if the screens were pre-assembled and ZBMmed for download and the link package followed in the background ? Or maybe only the first screen followed by it's link package etc. etc. That would be a way to get some action in only 4 to 5 Sec.! It also seems like a way to control EXACTLY what people see. Differing screen resolutions could present some difficulty in today's marketplace, but who knows what the future might bring ? - Clarence Verge - Using Arachne V1.62 for a change....
