23 Feb
2000
23 Feb
'00
1:46 a.m.
Is there any tool known to optimize GIF files in size
?
It hapened that I just changed some GIFs and without
changeing the content the files did grow. After some
research I found that the editor I used adds some headers
(or whatever) structures, increasing the file size.
Not a big increase, but if a 900 Byte picture grows
to 1100 I'd like to remove the overhead.
The best way is to convert the GIF into a "portable"
bitmap (i.e. nothing but the bits), then back into a
GIF again. I've been doing this for a decade with a package
called NetPBM:
NetPBM, GRAPHICS, Suite of graphic image format manipulation & conversion pgms
Enhanced portable bitmap toolkit. The PBMPLUS toolkit allows
conversions between image files of different format. By means of
using common intermediate formats, only 2 * N conversion filters
are required to support N distinct formats, instead of the N**2
which would be required to convert directly between any one format
and any other. The package also includes simple tools for
manipulating portable bitmaps.
As of the last release I built (early 90's), it was supposedly
available at:
* wuarchive.wustl.edu (128.252.135.4),
directory /graphics/graphics/packages/NetPBM
* ikaros.fysik4.kth.se (130.237.35.2), directory /pub/netpbm.
* ftp.informatik.uni-oldenburg.de (134.106.1.9). This site also carries
binaries for the Amiga.
* peipa.essex.ac.uk (155.245.115.161), directory ipa/src/manip
* ftp.rahul.net (192.160.13.1), directory /pub/davidsen/source
* ftp.cs.ubc.ca, directory /ftp/archive/netpbm
What *I* like about NetPBM is that it's a command-line tool, not
a "point-and-drool" graphics tool. This means that when I
have a few thousand images to convert (as I just did yesterday)
that I can do them all with a command script.
I especially like it for things like auto-cropping and
twiddling colormaps to make backgrounds be "transparent".
--
Tim Shoppa Email: shoppa(a)trailing-edge.com
Trailing Edge Technology WWW: http://www.trailing-edge.com/
7328 Bradley Blvd Voice: 301-767-5917
Bethesda, MD, USA 20817 Fax: 301-767-5927