http://www.jpeg.org/ is the official home for JPEG, a graphical file format that incorporates lossy still image compression. The Img package supports this format.
The GWImage widget supports this format.
The name comes from the name of the group that developed the format: the Joint Photographic Experts Group. It is extremely well suited to compression of real-world images, though if you intend to do substantial manipulation you are better off using a non-lossy compression scheme instead (such as is found in the TIFF format with the right options.)
Greyscale images are compressible (AIUI) in a lossless fashion as JPEG images; I think this is using a different algorithm and you might need to select the correct algorithm when doing the compression (though some utilities will scan the image first to see if this is possible.) Files in this format frequently have an extension of .jpg .
LV What is jbig ? I've seen a reference to this library in a recent application, but I've not been able to locate a library to build that supports it. LV Also, what is JPEG 2000? I notice that http://j2000.org/ and http://www.tele.ucl.ac.be/PROJECTS/OPENJPEG/main.html have what appear to be independent toolkits for it. Is anyone doing work to bind it to Tk - perhaps via Tkimg?
And now, JPEG enters the intellectual properties legal swamp:
Forgent Sues Over JPEG Patent (Business 2:00 a.m. PDT) http://go.hotwired.com/news/business/0,1367,63200,00.html/wn_ascii
Forgent Networks says it owns a key algorithm in the JPEG picture format, and intends to get 31 of the computing industry's biggest companies to pay for it.
ALOVE Realistically speaking, probably billions of web pages have been using jpegs for many years, so even if this Forgent Networks lawsuit got anywhere, it would be in the courts for years. In other words, don't worry about it. ^_^
See also Reading JPEG Image dimensions, Reading JPEG comments, Writing JPEG comments
As of 22 May 2004 JPEG is a module in tcllib that incorporates the above functions as well as a few more. Documentation may be found at http://tcllib.sourceforge.net/doc/jpeg.html
