Doug Franklin wrote:
On Wed, 15 Jun 2005 16:38:13 +0200, Toralf Lund wrote:
I'm not sure the traditional JPEG files support this kind of
compression [lossless] even in theory.
According to my "Encyclopedia of Graphic File Formats" (Murray and van
Ryper, 1996) it did.
"The JPEG standard does offer a separate lossless mode.
This mode has nothing in common with the regular DCT-
[Discrete Cosine Transform] based algorithms, and it is
currently implemented only in a few commercial
applications." [page 200]
Yes, but isn't that "the JPEG standard" as in the *compression
standard*, as opposed to the file format? The fact that a compression
scheme is defined by the JPEG does not necessarily imply that it is
allowed in a format described by the same group. In fact, at least some
of the work on lossless compression was done after the file format was
defined.
- Toralf
