Grösse von png-Bilder verkleinern
Möchte man die Grösse von png-Bilder verkleinern, kann pngcrush dazu verwendet werden. Im FreeBSD-Portbaum findet man pngcrush unter graphics/pngcrush:
# cd /usr/ports/graphics/pngcrush && make install clean
Benutzer von pkgng können pngcrush wie folgt installieren:
# pkg install pngcrush
Mit der -e Option kann der Suffix der verkleinerten Datei angegeben werden, danach optimiert pngcrush die png-Datei und speichert die verkleinerte Datei mit dem entsprechenden Suffix:
# pngcrush -e -opt.png photo.png
| pngcrush 1.7.24
| Copyright (C) 1998-2002,2006-2012 Glenn Randers-Pehrson
| Portions copyright (C) 2005 Greg Roelofs
| This is a free, open-source program. Permission is irrevocably
| granted to everyone to use this version of pngcrush without
| payment of any fee.
| Executable name is pngcrush
| It was built with libpng version 1.4.11, and is
| running with libpng version 1.4.11 - March 29, 2012
| Copyright (C) 1998-2004, 2006-2012 Glenn Randers-Pehrson,
| Copyright (C) 1996, 1997 Andreas Dilger,
| Copyright (C) 1995, Guy Eric Schalnat, Group 42 Inc.,
| and zlib version 1.2.5, Copyright (C) 1995-2010 (or later),
| Jean-loup Gailly and Mark Adler.
| It was compiled with gcc version 4.2.1 20070831 patched [FreeBSD].
Recompressing photo.png
Total length of data found in IDAT chunks = 169558
IDAT length with method 1 (fm 0 zl 4 zs 0) = 113517
IDAT length with method 2 (fm 1 zl 4 zs 0) = 128112
IDAT length with method 3 (fm 5 zl 4 zs 1) = 182436
IDAT length with method 4 (fm 0 zl 9 zs 1) = 119126
IDAT length with method 7 (fm 0 zl 9 zs 0) = 95461
Best pngcrush method = 7 (fm 0 zl 9 zs 0)
for photo-opt.png
(43.70% IDAT reduction)
(42.80% filesize reduction)
CPU time decoding 0.117, encoding 0.273, other 0.031, total 0.422 seconds
# ls -lart *png
-rw-r--r-- 1 beat beat 173775 Jun 2 20:11 photo.png
-rw-r--r-- 1 beat beat 99406 Jun 2 20:14 photo-opt.png
Mehr Informationen zu pngcrush erhält man mit der -h Option.