P.J. Alling wrote: >What's wrong with it? Well it was supposed to replace the jpeg and gif >standards in web pages, (when it looked like jpeg might have been >patented and of gif always had always been owned by CompuServe IIRC and >there were threats of lawsuits over licensing), both of which ware >relatively lightweight image files that should be used for different >purposes. PNG tries to replace both and does it badly, and also can be >used as a general purpose editing format, so it also want's to be a Tiff >or maybe a PSD file. If they had just tried to make a lossless >equivalent of Jpeg, (and isn't there a JPEG 2000, standard that's >supposed to be lossless, anyway which while larger than normal jpegs is >still much smaller than PNG), The designers tried to put too much into >it, and almost no one uses it, now that the threat to users of jpegs and >gifs has receded.
Almost all of that is wrong. The 8-bit version of PNG (PNG-8) was intended to replace GIF with a non-proprietary format that offered smaller file size. In that it succeed almost completely. It's non-proprietary and if makes for smaller files except for a few cases with really small images. I don't know any web designer who uses GIF for still graphics any more, PNG-8 is near universal. PNG-24 was never intended to replace JPEG for photographs for web purposes. The main purpose of PNG-24 is graphic design images (as opposed to photographic images) which require alpha channel transparency. Neither JPEG nor GIF can do that at all. No form of PNG was ever intended to replace PSD or TIFF (PNG stands for Portable Network Graphics) - PNG doesn't support layers and though it theoretically does support embedded ICC profiles, I don't know of any software that will embed profiles in PNGs. JPEG2000 had multiple compression options, one of which was lossless, but it was generally less efficient than PNG. -- Mark Roberts - Photography & Multimedia www.robertstech.com -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
