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OPT-JPG

NAME
SYNOPSIS
DESCRIPTION
OPTIONS
EXAMPLES
NOTES
SEE ALSO
COPYRIGHT

NAME

opt-jpg − losslessly optimize JPEG image files

SYNOPSIS

opt-jpg [−a(rithmetic)] [−g(ray)] [−h(elp)] [−m markers_to_copy] [−q(uiet)] [−t(ouch)] file...

DESCRIPTION

opt-jpg losslessly optimizes JPEG images. This is accomplished using a combination of the filesize, jpegtran, and tempname utilities.

OPTIONS

−a

Allow arithmetic coding to be used on re-written image files instead of the more prevalent Huffman coding. This can yield image files that are 5-7% smaller, but older software (image viewers, web browsers, image editors) might not read them successfully. USE WITH CAUTION.

−g

Force the output to grayscale.

−h

Print help and quit.

−m

Copy no markers from source file. Identical to "-copy none" option from jpegtran. This is the default.

−m comments

Copy only comment markers. Identical to "-copy comments" option from jpegtran.

−m all

Copy all extra markers. Identical to "-copy all" option from jpegtran.

−q

Quiet output. No output commentary will be printed.

−t

Preserve timestamp on modified files.

EXAMPLES

Optimize a couple of image files:

opt-jpg image001.jpg image002.jpg

Optimize all JPEG images in an entire directory tree:

find . -name "*.jpg" -exec opt-jpg {} \;

Or alternatively, optimize all JPEG images this way:

find . -name "*.jpg" -print0 | xargs -0 opt-jpg

Fully utilize a quad-core system while optimizing all JPEG images:

find . -name "*.jpg" -print0 | xargs -0 -n 1 -P 4 opt-jpg
find . -name "*.jpg" | parallel opt-jpg

NOTES

This program may create progressive JPEG files from images that were previously non-progressive. Curiously, they are sometimes smaller.

SEE ALSO

filesize(1), jpegtran(1), tempname(1)

COPYRIGHT

Copyright (C) 2004-2021 by Brian Lindholm. This program is free software; you can use it, redistribute it, and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3, or (at your option) any later version.

This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.