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#! /bin/sh /usr/share/dpatch/dpatch-run
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## 204_jpegtran_man.dpatch by Jorgen Grahn <grahn+debian@snipabacken.dyndns.org>
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## All lines beginning with `## DP:' are a description of the patch.
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## DP: improves readability of jpegtran man page
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diff -urNad libjpeg6b-6b~/jpegtran.1 libjpeg6b-6b/jpegtran.1
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--- libjpeg6b-6b~/jpegtran.1 2007-08-16 22:55:43.000000000 +0200
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+++ libjpeg6b-6b/jpegtran.1 2007-08-16 22:55:50.000000000 +0200
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Transverse transpose (across UR-to-LL axis).
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The transpose transformation has no restrictions regarding image dimensions.
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The other transformations operate rather oddly if the image dimensions are not
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a multiple of the iMCU size (usually 8 or 16 pixels), because they can only
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transform complete blocks of DCT coefficient data in the desired way.
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default behavior when transforming an odd-size image is designed
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to preserve exact reversibility and mathematical consistency of the
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of transpose and flip operations; for consistency, their actions on edge
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pixels are defined to be the same as the end result of the corresponding
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transpose-and-flip sequence.
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For practical use, you may prefer to discard any untransformable edge pixels
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rather than having a strange-looking strip along the right and/or bottom edges
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of a transformed image. To do this, add the
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Drop non-transformable edge blocks.
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Obviously, a transformation with
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is not reversible, so strictly speaking
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If you are only interested by perfect transformation, add the
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Fails with an error if the transformation is not perfect. For example
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.B (jpegtran \-rot 90 -perfect foo.jpg || djpeg foo.jpg| pnmflip \-r90 | cjpeg)
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to do a perfect rotation if available or an approximated one if
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corner up and/or left to make it so, simultaneously increasing the region
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dimensions to keep the lower right crop corner unchanged. (Thus, the
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output image covers at least the requested region, but may cover more.)
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are enhancements from http://sylvana.net/jpegcrop/ that may not be available on
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The image can be losslessly cropped by giving the switch:
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Crop to a rectangular subarea of width W, height H starting at point X,Y.
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Another not-strictly-lossless transformation switch is:
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Force grayscale output.
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This option discards the chrominance channels if the input image is YCbCr
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(ie, a standard color JPEG), resulting in a grayscale JPEG file. The
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luminance channel is preserved exactly, so this is a better method of reducing
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Copy all extra markers. This setting preserves miscellaneous markers
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-found in the source file, such as JFIF thumbnails and Photoshop settings.
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+found in the source file, such as
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+JFIF thumbnails and Photoshop settings.
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In some files these extra markers can be sizable.
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The default behavior is
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.BR "\-copy comments" .
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(Note: in IJG releases v6 and v6a,
added
removed
debian/patches/204_jpegtran_man.dpatch
