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