I'm using 'convert' to rotate PNG images and having trouble in that the
file size has grown significantly after the rotation.
I start out with an image like:
[~/] file MD628_1958_AUG_IONOGRAM_3770.png
MD628_1958_AUG_IONOGRAM_3770.png: PNG image data, 4749 x 2368, 8-bit
grayscale, non-interlaced
[~/] ls -l MD628_1958_AUG_IONOGRAM_3770.png
-rwxrwxr-x 1 robr robr 5650805 May 21 10:54
MD628_1958_AUG_IONOGRAM_3770.png
Original image can be obtained here
<http://ideas.ngdc.noaa.gov/share/rob/Ionosonde/CDMP/MD628_1958_AUG_IONOGRAM_3770.png>
if you are interested.
I'm trying to rotate this PNG, while preserving the file type, and bit
depth and maximizing lossless compression:
[~/] convert -verbose -rotate 180 -quality 100
MD628_1958_AUG_IONOGRAM_3770.png
MD628_1958_AUG_IONOGRAM_3770-quality100_rotated.png
MD628_1958_AUG_IONOGRAM_3770.png PNG 4749x2368 4749x2368+0+0
PseudoClass 256c 5.4mb
MD628_1958_AUG_IONOGRAM_3770.png=>MD628_1958_AUG_IONOGRAM_3770-quality100_rotated.png
PNG 4749x2368 4749x2368+0+0 PseudoClass 256c 7.4mb 3.950u 0:05
Unfortunately, the file size has grown ~50%
[~/] file MD628_1958_AUG_IONOGRAM_3770-quality100_rotated.png
MD628_1958_AUG_IONOGRAM_3770-quality100_rotated.png: PNG image data,
4749 x 2368, 16-bit grayscale, non-interlaced
[~/] ls -l MD628_1958_AUG_IONOGRAM_3770-quality100_rotated.png
-rw-rw-r-- 1 robr robr 7805611 May 21 11:55
MD628_1958_AUG_IONOGRAM_3770-quality100_rotated.png
Any ideas?
System info:
uname -a
Linux ... 2.6.18-53.1.19.el5 #1 SMP Tue Apr 22 03:01:10 EDT 2008
x86_64 x86_64 x86_64 GNU/Linux
convert -version
Version: ImageMagick 6.2.8 03/31/08 Q16
file:/usr/share/ImageMagick-6.2.8/doc/index.html
Copyright: Copyright (C) 1999-2006 ImageMagick Studio LLC
Thanks!
--
Rob Redmon - Physicist - Ionosphere
NOAA/NGDC
325 Broadway E/GC2
Boulder, Colorado 80305
Tel: (303) 497-4331
Fax: (303) 497-6513
[EMAIL PROTECTED]
"Engineering is the art of making what you want from things you can get."
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