Type negotiation within image formats

Ka-Ping Yee (kryee@novice.uwaterloo.ca)
Fri, 8 Mar 1996 12:31:03 -0500

Date: Fri, 8 Mar 1996 12:31:03 -0500
From: Ka-Ping Yee <kryee@novice.uwaterloo.ca>
Message-Id: <199603081731.MAA01404@novice.uwaterloo.ca>
To: www-html@w3.org
Subject: Type negotiation within image formats

I know that this issue doesn't belong exactly in a group discussing HTML,
but it arose when authoring an HTML document, so i suspect some of you
may have encountered the same problem.  I'd appreciate it if you could
provide some of your own solutions or answers and/or direct me to the
appropriate forum.

Is there an established mechanism for negotiating the type of an image,
*within* identical Content-Type values?  For instance, suppose i have
an image i wish to serve as a GIF; if i serve it in colour, then people
with black-and-white displays will experience horrible dithering effects,
making some of the text illegible; but if i serve it in black-and-white,
information is lost.  Even if i create a black-and-white image for
maximum legibility along with the colour image, both images are

Content-Type: image/gif

Do there exist agreed-upon values for "; type=..." after the above header
which could be generated by a user agent (which determines the capabilities
of its display) which cause content negotiation to happen?

How else has this problem been solved before?


Ping (Ka-Ping Yee):  3A Computer Engineering, University of Waterloo, Canada
kryee@csclub.uwaterloo.ca, St. Paul's College, Waterloo N2L 3G5, 519 7258008
CWSF 89 90 92; LIYSF 90 91; Shad Valley 92; DOE 93; IMO 91 93; ACMICPC 94 96