[clean-list] Generating textures in Clean

[Marco Kesseler]

Date sent:      	Mon, 05 Nov 2001 10:18:54 +0100
From:           	Jerzy Karczmarczuk <karczma@info.unicaen.fr>
Organization:   	Université de Caen, France
Copies to:      	clean-list@cs.kun.nl
Subject:        	[clean-list] Generating textures in Clean

> I have a special offer for him. A Clean package which generates
> procedural textures. Something which has been partially inspired
> by Conal Elliot's PAN package (although I started earlier, and 
> used my stuff just for teaching, having never written a single
> line of documentation...)

For Jerzy in particular:

Having drooled over the pictures in the documentation, and seeing 
that one of the wishes is loading JPEG files, I am considering 
having a look at your bmp handling code and building a JPEG-
>BMP converter from the JPEG decoder I already have. This 
however only makes sense in case Clastic can deal with RGB 
BMPs (which I am not sure of). Seems almost trivial in that case. I 
am currently NOT considering implementation of colour reduction 
(That, and the LZW patents are also the reason that the JPEG 
decoder does not convert to GIF).

For Everybody:
 
I have encountered files that the JPEG decoder cannot (yet) 
decode. Point is that there seems to be a gap between:
- the published standards (JPEG, JFIF).
- the reality.

One problem of reality is application specific markers. I do know a 
tiny bit about some Adobe extensions, but virtually nothing about 
others. If anyone has information about application-specific 
markers in JPEG files (in particular the ones that say 'hey this is a 
thumbnail', or 'hey this is the main picture'), please let me know, 
and I will consider adding support for it. This shouldn't be too 
difficult in general.

Another problem is that some baseline JPEG files do not even 
seem to adhere to the standards (multiple SOI's without matching 
EOI's - or I am misreading the standards). I am willing to add 
heuristics.

And then, there are also non-baseline JPEG files. Well, then you 
have run out of luck, unless you add the support yourself.

regards,
Marco
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