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SGI Developer Toolbox 6.1
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README.sgi
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~4Dgifts/toolbox/src/haeberli/jpeg README.sgi
This directory contains the fourth public release of the Independent
JPEG Group's free JPEG file format image compression/decompression
software including images of libjpeg.a, cjpeg, and djpeg. JPEG is a
standardized compression method for full-color and gray-scale images.
JPEG is intended for compressing "real-world" scenes; cartoons and
other non-realistic images are not its strong suit. JPEG is lossy,
meaning that the output image is not necessarily identical to the
input image. Hence you must not use JPEG if you have to have
identical output bits. However, on typical images of real-world
scenes, very good compression levels can be obtained with no visible
change, and amazingly high compression levels are possible if you
can tolerate a low-quality image.
Along with the fourth public release of the Independent JPEG Group's
free JPEG software, support has been added to manipulate SGI image files
to/from jpeg format. To compress an SGI image file, simply name the SGI
image file on the cjpeg command line:
cjpeg in.rgb > in.jpg
in.jpg will contain the compressed image
To decompress a .jpg image into an SGI image file specify -sgi on the
djpeg command line:
djpeg -sgi < in.jpg > out.rgb
You can view/compare the difference between the two images using movie:
movie in.rgb out.rgb -z 2