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opt-jpg(1)                                                          opt-jpg(1)




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  suc-
              cessfully.  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) 2004-2020 by Brian Lindholm.  This program is free soft-
       ware; 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 MER-
       CHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  General
       Public License for more details.



littleutils                       2020 Oct 19                       opt-jpg(1)

littleutils 1.2.3 - Generated Tue Dec 1 16:41:04 CST 2020
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