Message-Id: <mailto:199507171515.KAA15822@library.wustl.edu> Date: Mon, 17 Jul 1995 11:12:31 -0400 From: Karen Strom <mailto:kstrom@HANKSVILLE.PHAST.UMASS.EDU> Subject: Gif inline images in WWW pages To: Multiple recipients of list IMAGELIB
I am responding to Pamela Mason's post at the request of Stuart Glogoff of the University of Arizona Library.Browsers do indeed treat images differently than specialized image viewers, and how many colors each of these viewers may have allocated may be a function of operating system. Browsers typically set a maximum number of colors that may be used by any image displayed there. 50 is a typical number, not 8. The remaining colors are shown as the "closest" color among those used. This is also true of many image viewers, which use as many colors as they can obtain from the system, but perhaps not as many as requested by the image.
The size of a GIF image does scale with color, but simply because having fewer colors in an image means that it is more probable that there are multiple identically colored pixels adjacent in the same image line. To understand this you must understand the was the GIF image compression algorithm works.
For the use of people placing WWW pages online, I have prepared a small tutorial on the preparation of GIF images for inline use. This tutorial contines hyperlinked references to an article by Frans van Hoesel who prepared the Expo exhibits and links to the necessary software and a few sites where the image manipulation will be done for you.
The URL is:
http://hanksville.phast.umass.edu/~kstrom/tutorials/images.html
As an additional note, Mosaic (at least for X) now supports inline color JPEGs. However, they seem to have forgotten to also implement greyscale JPEGs as well.
Karen M. Strom **************************************************************************** Karen Strom mailto:kstrom@hanksville.phast.umass.edu Research Professor Voice: 413-545-2131 Five College Astronomy Dept. FAX: 413-545-4223 University of Massachusetts http://www-astro.phast.umass.edu/ Amherst, MA 01003 http://hanksville.phast.umass.edu/ pgp fingerprint: 91 ED E0 00 DC C4 5F 2A AE FD B0 F7 21 8E 85 F8 ****************************************************************************