----------------------------Original message---------------------------- Krishna asks about compression algorithms, lossy versus lossless and related matters. First let me suggest that you download a paper from my website. It's on the page at: http://www.ioa.ucla.edu/~hetrick/vrh001.htm The title is Designing a WorldWide Web Site: Graphic Formats on the WorldWide Web You'll also to download the Adobe Acrobat Reader if you don't already have it. In this paper, my coauthor and I discuss the issues of images for people who are (as they say at Scientific American) educated laymen, but not necessarily computer dudes or dudettes. It may sound pretty strange, but the issue is really pretty straightforward. If you want to maintain absolute accuracy of digital materials, there are relatively few mechanisms for compressing images very much at all. The storage mechanisms for most of these will be something pretty huge. None of the "popular" file formats is lossless. You are likely to need to stick with formats like .tga (Targa), .rle (Run-Length-Encoded), or .pcx (PhotoPaint). If you want to maintain "looks", the issue is what are you going to to with them. If it's to display them on the Web with a fair degree of accuracy, then the choice of .jpeg (usually .jpg in the PC world to fit with 8.3 naming conventions) at highest quality is pretty reasonable. It's even pretty reasonable to use these for images that you might think would more logically go as .gif files. The really big issue from the standpoint of a Webmaster is that the files should download fast and have "high" quality. That can most easily be accomplished with .jpeg files. You should be aware that there is a new standard called .png (portable network graphics) coming and that it combines the best features of .jpeg with the best features of .gif files. It's not yet clear exactly when this will be available in browsers. My best guess is that it will be late this year or early 1999 when the features of HTML 4 are fully implemented. As soon as we have some functional "popular" software to do similar measurements as we did with .gif, .jpg, and .pcd files, we will add them to our list of measures. HTH. vh -- \ / Virginia R. Hetrick, here in sunny California 0 Bellnet: 310.206.7588 Oo Email: [log in to unmask] http://www.ioa.ucla.edu/~hetrick Site of the month: http://www.2chicks.org/