Hi again,
It was written:
>> Isn't there a JPG file viewer for MSX?
>>
>> Yes there are few, thank god. I'm just suprised, that nobody
has done one
>> for GFX9000. (This is a tip for someone)
>>
>>Ok, I can do that. If someone can tell me about the JPG-format,
that is.
>>(this is a question for someone)
>>
>> U can find JPEG specifications in ftp://x2.ouli.fi.
>>
> Doesn't work. Are you sure it's the right address?
Doesn't work for me either, because I don't (yet) have direct FTP
access... ;-(
The JPEG file format is in fact 2 things:
-The JPEG compression method
-The .JPG/JPEG/JFIF file format
The JPEG compression method is standardised in some ISO standard
(ISO/IEC 10918 part 1), but: you can -order- this for $$$..., it's
not (officially) on the web. But do some looking around, and you
might find some pirate copies out there.
For these kind of things I consider that a good thing, it's
ridiculous that first a lot of people & companies get together to
develop such standards for the 'common good', after which some
standard organisation like ISO goes out and sells copies of the final
documents for xx $$$ a piece. So I really don't mind if some people
stick some 'unofficial' copies of such things on their webpages....
BTW. the compression method itself is free to use, just this ISO
document specifying it is copyrighted.
Only this ISO standard didn't specify an actual file format (!), just
the compression method. Some company (C-Cube microsystems,
www.c-cube.com, don't bother looking there) defined the JFIF file
format, which does define the file format, and is a 'basic'
application of this JPEG compression method. This file format is
what's been used for most actual .JPG files.
What should be easy to obtain:
-This JFIF file format specification
-Sample compression/decompression source codes
Some links:
http://www.jpeg.org JPEG home page
not much here but some usefull links
http://www.w3.org/Graphics/JPEG/jfif.txt JFIF 1.02 spec's
http://ftp.sunet.se/pub/simtelnet/msdos/graphics/jpegsr6b.zip
sample JPEG compression/decompression source codes, from the
Independent JPEG Group (www.ijg.org)
Well, that's the easy part. I think for JPEG, the file format would
be easy. The (de)compression method is the hard part, coooommplicated
& CPU-intensive (good luck).
P.S. Who not do a PNG (Portable Network Graphics, the
'GIF-replacement-to-be') encoder/decoder instead?
Alwin Henseler ([EMAIL PROTECTED])
http://huizen.dds.nl/~alwinh/msx (MSX Tech Doc page)
http://www.twente.nl/~cce/index.htm (Computerclub Enschede)
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