In article <1992Nov13.134656.21707@noose.ecn.purdue.edu>, henstock@ecn.purdue.edu (Peter V Henstock) writes:
|>From: henstock@ecn.purdue.edu (Peter V Henstock)
|>Subject: JPEG image viewing in Hypercard
|>Organization: Purdue University Engineering Computer Network
|>Lines: 9
|>
|>Anybody have any information or know where to find a JPEG
|>viewer for use from Hypercard. We have a viewer which does
|>GIF's but we are setting up a picture database which will eat
|>up too much space so we're trying to use JPEGs only we cannot
|>locate a viewer.
|>
|>Thanks in advance,
|>
|>--Peter
|>
We have been using the JPEG compressor in QuickTime and the Hypercard
"picture" XCMD that ships with HC with good success. We get typical
compression ratios from, 6:1 to 12:1 without noticable degradation
(depending on the particular image). The "picture" XCMD accesses
compressed PICTs and uncompressed PICTs transparently; QuickTime
takes care of it.
However, be aware that you need processor power and memory for the
decompression. Also, this compression is "lossy", so the decompressed
image is not bit-for-bit identical to the original. This usually
is not a problem if all you want it to display the image (and your
application is not e.g. medical imaging); but we have found that
decompressing a picture, modifying it (for example by adding callouts), and recompressing it can lead to noticable artifacts (unwanted color blotches).
In short, we have come to the conclusion that lossy compressed images are
not really "archival" quality. So we maintain an archive of never-compressed images, but use compressed ones for every-day...
--
Joshua Yeidel | yeidel@tomar.accs.wsu.edu
Academic Computing Services | All standard disclaimers apply
Washington State University | "Believe it if you need it,
Pullman, WA 99164-1226 | or leave it if you dare..."
