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rot-jpg(1)                                                          rot-jpg(1)




NAME

       rot-jpg - losslessly rotate JPEG images by 90, 180, or 270 degrees


SYNOPSIS

       rot-jpg  [-f(ast)] [-h(elp)] [-l(eft)] [-r(ight)] [-t(ouch)] [-u(pside-
       down)] file...


DESCRIPTION

       rot-jpg losslessly rotates JPEG images using the jpegtran, opt-jpg, and
       tempname utilities.


OPTIONS

       -f     Run  faster by skipping the opt-jpg post-processing that is nor-
              mally performed.

       -h     Print help and quit.

       -l     Rotate image by 270 degrees clockwise.  In other words, spin the
              top of the image to the left.

       -r     Rotate  image by 90 degrees clockwise.  In other words, spin the
              top of the image to the right.

       -t     Preserve timestamp on modified files.

       -u     Rotate image by 180 degrees clockwise.  In other words, spin the
              image upside-down.


EXAMPLES

       Spin a couple of image files to the left:
              rot-jpg -l image001.jpg image002.jpg

       Spin all JPG images in an entire directory tree to the right:
              find . -name "*.jpg" -exec rot-jpg -r {} \;

       Or alternatively, spin all JPG images to the right this way:
              find . -name "*.jpg" -print0 | xargs -0 rot-jpg -r

       Fully utilize a quad-core system to spin all images upside-down:
              find . -name "*.jpg" -print0 | xargs -0 -n 1 -P 4 rot-jpg -u
              find . -name "*.jpg" | parallel rot-jpg -u


WARNING

       The  rotation  performed  by rot-jpg is perfectly lossless if the image
       dimensions are an exact multiple of the JPEG iMCU size (usually 8 or 16
       pixels), which is normally the case with images coming out of a digital
       camera or cell phone.  However, if the image is not an exact  multiple,
       then  the  extra pixels at the right and/or bottom of the image will be
       cropped.  See the jpegtran manpage for more details.


SEE ALSO

       jpegtran(1), opt-jpg(1), tempname(1)


COPYRIGHT

       Copyright (C) 2019-2020 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                       rot-jpg(1)

littleutils 1.2.3 - Generated Mon Nov 30 19:32:47 CST 2020
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