Casio V-N500 User Manual
Page 233
E-231
RELATED SOFTWARE
==================
Numerous viewing and image manipulation programs now support JPEG. (Quite a few
of them use this library to do so.) The JPEG FAQ described above lists some of the more
popular free and shareware viewers, and tells where to obtain them on Internet.
If you are on a Unix machine, we highly recommend Jef Poskanzer’s free PBMPLUS
software, which provides many useful operations on PPM-format image fi les. In particular,
it can convert PPM images to and from a wide range of other formats, thus making cjpeg/
djpeg considerably more useful. The latest version is distributed by the NetPBM group,
and is available from numerous sites, notably ftp://wuarchive.wustl.edu/graphics/graphics/
packages/NetPBM/. Unfortunately PBMPLUS/NETPBM is not nearly as portable as
the IJG software is; you are likely to have diffi culty making it work on any non-Unix
machine.
A different free JPEG implementation, written by the PVRG group at Stanford, is available
from ftp://havefun.stanford.edu/pub/jpeg/. This program is designed for research and
experimentation rather than production use; it is slower, harder to use, and less portable
than the IJG code, but it is easier to read and modify. Also, the PVRG code supports
lossless JPEG, which we do not. (On the other hand, it doesn’t do progressive JPEG.)
FILE FORMAT WARS
=================
Some JPEG programs produce fi les that are not compatible with our library. The root of
the problem is that the ISO JPEG committee failed to specify a concrete fi le format. Some
vendors “fi lled in the blanks” on their own, creating proprietary formats that no one else
could read. (For example, none of the early commercial JPEG implementations for the
Macintosh were able to exchange compressed fi les.)
The file format we have adopted is called JFIF (see REFERENCES). This format has
been agreed to by a number of major commercial JPEG vendors, and it has become the
de facto standard. JFIF is a minimal or “low end” representation. We recommend the use
of TIFF/JPEG (TIFF revision 6.0 as modifi ed by TIFF Technical Note #2) for “high end”
applications that need to record a lot of additional data about an image. TIFF/JPEG is
fairly new and not yet widely supported, unfortunately.