[comp.graphics] Jpeg spec

malak@halluc.FIDONET.ORG (Michael Malak) (02/05/91)

Where is it I can request a copy of the JPEG specification?  I'd like to 
get a copy within a week if that's possible, as I'm up against a 
deadline for a paper I'm writing for the IEEE data compression 
conference.

If that's impossible, perhaps someone can give me anwer my main 
question: what provisions, if any, does JPEG have for 8-bit images (with 
look-up-table)?

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Michael Malak -- sysop of Hallucination (FidoNet node 1:109/345)

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dolf@fwi.uva.nl (Dolf Starreveld) (02/06/91)

malak@halluc.FIDONET.ORG (Michael Malak) writes:

> Where is it I can request a copy of the JPEG specification?  I'd like to 
> get a copy within a week if that's possible, as I'm up against a 
> deadline for a paper I'm writing for the IEEE data compression 
> conference.

> If that's impossible, perhaps someone can give me anwer my main 
> question: what provisions, if any, does JPEG have for 8-bit images (with 
> look-up-table)?
None! However, it is fairly easy, using the lookup table, to change all
pixels in an 8x8 sub-image to 24 bit RGB values, compress those using JPEG.
The decoder should, upon seeing the display is 8-bit, somehow determine
an optimal lookup table and translate the pixels back to indices in this
table.

--dolf
--
Dolf Starreveld  Phone: +31 20 592 5056/5022 (FAX: 5155), TELEX: 10262 HEF NL
EMAIL:           dolf@fwi.uva.nl (dolf%fwi.uva.nl@hp4nl.nluug.nl)
SNAIL:           Dept. of Math. and Computing Science, University of Amsterdam,
                 Kruislaan 403, NL-1098 SJ  Amsterdam, The Netherlands