Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!thunder.mcrcim.mcgill.edu!snorkelwacker.mit.edu!usc!julius.cs.uiuc.edu!wuarchive!uunet!gistdev!flint From: flint@gistdev.gist.com (Flint Pellett) Newsgroups: comp.graphics Subject: Re: JPEG alogorithm results Message-ID: <1051@gistdev.gist.com> Date: 10 Jan 91 19:15:39 GMT References: <1991Jan4.025552.810@allgfx.agi.oz> Organization: Global Information Systems Technology Inc., Savoy, IL Lines: 39 cn@allgfx.agi.oz (Con Neri) writes: >From: >You can obtain the JPEG draft from several places. It is still a draft >although some manufacturers have gone ahead and implemented the >algorithm in hardware (e.g. C-Cube Microsystems). One such place is >JPEG Draft Technical Specification >X3 Secretartiat: Computer and Business Equipment Manufacturers Association >311 First Street NW, Suite 500 >Washington, DC 20001-2178 >The JPEG (Joint Photographic Experts Group) draft standard implements a >DCT based image compression algorithm. The general ideas are very >standard and can be found in almost any image digital image processing >textbook. However, a lot of effort went into optimizing the algorithm >both for speed and subjective quality. Typical compression ratios are >around 30:1 for 24 bit RGB images with reasonably high resolution. >Higher compression ratios are of course selectable. The image quality >degrades quite gracefully as compression ratios are increased. This doesn't say how much time is required to do the uncompression. (I could care less if it takes 20 minutes to compress it, as long as it can be uncompressed rapidly.) Before JPEG can displace something like GIF, it's going to have to be able to uncompress images in something less than 5 seconds on a typical PC, (and obviously, if you want it to handle animation, you're going to have to get down in the fractional second range.) I've not seen any concrete data on decompression speed other than one article that quoted times around 2 minutes (yeech!) by some package I don't remember the name of. Can anyone who knows tell us what speed is available right now, both from software and from hardware solutions? Thanks. -- Flint Pellett, Global Information Systems Technology, Inc. 1800 Woodfield Drive, Savoy, IL 61874 (217) 352-1165 uunet!gistdev!flint or flint@gistdev.gist.com