opt-png(1) opt-png(1)
NAME
opt-png - losslessly optimize PNG image files
SYNOPSIS
opt-png [-g(ray)] [-h(elp)] [-q(uiet)] [-r(es) DPI] [-t(ouch)] file...
DESCRIPTION
opt-png losslessly optimizes PNG images by removing unused palette
entries and/or optimizing the filtering algorithm. This is accom-
plished using a combination of the filesize, pngcrush, pngrecolor,
pngstrip, and tempname utilities.
OPTIONS
-g Force output to grayscale.
-h Print help and quit.
-q Quiet output. No output commentary will be printed.
-r DPI Write the specified resolution into the pHYs chunk of the output
file. Units are in pixels-per-inch. To convert from pixels-
per-meter, multiply by 0.0254 (or divide by 39.37). Note that
this does not change the number of pixels in the image. It only
changes the assumed size of the pixels.
-t Preserve timestamp on modified files.
EXAMPLES
Optimize a couple of image files:
opt-png image001.png image002.png
Optimize all PNG images in an entire directory tree:
find . -name "*.png" -exec opt-png {} \;
Or alternatively, optimize all PNG images this way:
find . -name "*.png" -print0 | xargs -0 opt-png
Fully utilize a quad-core system while optimizing all PNG images:
find . -name "*.png" -print0 | xargs -0 -n 1 -P 4 opt-png
find . -name "*.png" | parallel opt-png
NOTES
If at all possible, make sure that pngcrush version 1.6.x or later is
running on your computer. It performs substantially better than
pngcrush 1.5.10 (and earlier) on black-and-white (and other low-color)
images due to use of the Z_RLE zlib strategy.
SEE ALSO
filesize(1), pngcrush(1), pngrecolor(1), pngstrip(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-png(1)
littleutils 1.2.3 - Generated Thu Dec 3 07:41:27 CST 2020