This package contains programs for manipulating JPEG files: cjpeg/djpeg: convert to/from the JPEG file format rdjpgcom/wrjpgcom: read/write comments in JPEG files jpegtran: lossless transformations of JPEG files
Ian B. suggested libjpen-progs. I haven't tried it myself.
libjpeg-progs contains a few command-line scripts:
- cjpeg/djpeg: convert to/from the JPEG file format
- rdjpgcom/wrjpgcom: read/write comments in JPEG files
- jpegtran: lossless transformations of JPEG files
One of the more interesting is jpegtran. Most programs that manipulate images are format-neutral, so they'll decode the jpeg, do the transformation, then reencode -- which means you've double-encoded the file, and you'll have more jpeg distortion; jpegtran can rotate and flip your jpegs without any loss of quality.
More information on this package can be found on the Debian web site.
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