Software to implement JPEG image compression and decompression. JPEG pronounced "jay-peg") is a standardized compression method for full-color and gray-scale images. JPEG is intended for compressing "real-world" scenes (most of the time there are pictures that have been scanned-in with a scanner). Cartoons and other non-realistic images are not its strong suit. You should note that the output of JPEG is not necessarily the same as its input. If this is a factor for you, then don't use it. With typical real-world scenes, JPEG can achieve high compression rates, without noticeable differences. If you can accept pictures of lower quality, JPEG can achieve amazingly high compression rates.
There are some library functions available for reading and writing JPEG files. The 'cjpeg' and 'djpeg' applications use the library to make conversions between JPEG and other popular graphics file formats possible. The library is meant to be used within other applications.
Cjpeg compresses the input file, or standard input if no filename was given, and produces a JPEG/JFIF to standard output. Currently supported input file formats include: PPM (PBMPLUS color format), PGM (PBMPLUS Grayscale format), BMP, GIF, Targa and RLE (Utah Raster Toolkit Format). (RLE is only supported if the RLE library is available.) Djpeg decompresses a JPEG file in one of the above mentioned formats.