Message-Id: <mailto:199410131951.OAA25250@library.wustl.edu> Date: Thu, 13 Oct 1994 14:54:00 CDT From: "Hendershot, Gary" <mailto:GHENDERS@JA2.JSC.NASA.GOV> Subject: Image Alchemy To: Multiple recipients of list IMAGELIB <mailto:IMAGELIB@ARIZVM1.BITNET>
Geoff writes:> Thanks for that little tip!
> Any chance this little thing will make half a million little thumbnails
> out of a half a million images automatically?
Certainly. Let's take a _hypothetical_ case where you want to convert a bunch of electronic photographs of people saved in TARGA-24 format -- which is a 24-bit color (so-called "true color") file format -- and these electronic photographs have a spatial resolution (i.e. -- X, Y) of 1024 x 1280 pixels. And let say that what you need are 8-bit color GIF files with a spatial resolution of 128 x 160 pixels to be used as "thumbnail" images for a database, or home page on a WWW server, or whatever.
Providing that Image Alchemy is in a path-ed directory, and that you are currently logged to a working directory full of TARGA-24 files, the Image Alchemy command line would be simply:
ALCHEMY -g -X:128 -Y:160 *.TGA
The process would be that each TARGA-24 file would be read-in, scaled and color reduced to a default 8-bits, and finally saved in standard GIF format (actually GIF 87a format to be specific). You could have chosen a plethora of other options like special palettes, scaling while preserving aspect ratio, different algorithms for color reduction, just to name a few !
If you are serious about converting mass numbers of image files, it is best to work with blocks of files in separate directories -- like 2,000 or 3,000 per directory -- depending on the hard drive you are using (sector size can come into play here). MSDOS currently has a limitation of 2048 megabytes per partition. Magneto-optical storage comes in handy here, especially with the new 1.3 gigabyte MaxOptix 5-1/4" drives (and 2.0 gigabyte units coming in about a year). You could also read and then write back to a network file server's hard drive or magneto-optical.
-Gary H-
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ mailto:ghenders@JA2.JSC.NASA.GOV NASA / Johnson Space Center, Image Sciences Division -- Digital Imaging Laboratory Gary L. Hendershot, (713) 483-2144 NASA / JSC, Building 8, Room 244, PS4/RMS, Houston, TX 77058-3691 USA +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+