Travis Crump wrote: > Al Rider wrote: > >> I read thru these ramblings and don't still don't know why, in theory, >> the color space should be rendered with any modification at all. >> >> Rendering of html and css colors, yes that requires gamma consider, etc. >> However, the answer is simple [unfortunately] just replicate IE. 90% >> of the browsers are IE, so designers pick colors that look good with >> IE; period. >> >> As I understand it, PNG is a compression algorithm. Therefore, the >> decompression algorithm should repoduce the orginal, without any >> modification. > > > I would be surprised(but I don't know for sure) if PNG compression was > not lousy. I don't know how PNG works, but if it is lousy(like video > compression as opposed to lossless compression like zip or bz2) than it > would be _impossible_ for a decompression algorithm to reproduce the > original without modification. >
Why not find out the truth, rather than just guessing;-) http://www.libpng.org/pub/png/pngintro.html PNG is a bitmap image format. It supports a variety of bits-per-pixel RBG, and also indexed colour like GIF. It supports full alpha channel transparency, as well as simple on-off transparency or fully opaque. It allows you to include colour calibration information, either full information or just gamma correction, which means that images can look the same on both Macs and PCs. It supports optional interlacing. It uses lossless compression, based on zlib, which is the same library that gzip is built on. It can also do clever stuff (filters) before sending the data to zlib to make the files even smaller whist still being lossless. Some people get confused because you can do 'lossy compression' when you create PNG's. For instance you might take you 24bpp bitmap and convert it to a 256 colour indexed image before saving it, in order to create a smaller file. Tim.
