WHOA!! Backup the JPG truck...

[P3D Jonathan Gross <catalyst@xxxxxxxxxxxx>]

Dan Shelley wrote:
> It's an anaglyph saved at 100% quality (0% compression). THe images were
> both originally from a Photo-CD, used at thier highest resolutions. I
> think it's pretty clear myself...
> 
> JPG's can be used quite effectively for anaglpyhs IMHO.

I agree with you, but what are the advantages left from JPEG for image
compression?

For loss-less image compression, seperate out the RGB into three 8-bit
image channels, and compress each channel using a loss-less LZW (PKZIP)
method. You'll get between 3:1 and 5:1 compression with no loss of
important boundary data.

And, for high quality stereo pairs you might want to use 1024X768 field
pairs.  If people published their JPEG and JPS images with 0%
compression and 2X1024X768 resolution, then it might not be so bad.  But
is that what people are doing?

How about alignment information?  Without it, it's like handing someone
two loose film chips and asking them to look at the stereograph.  In
that respect, two JPEG images are better than one JPS pair.  At least
you can input them into an alignment utility without having to seperate
them first.

All of a sudden, a special format for stereo pairs doesn't look so bad; 
High quality loss-less compression, non-destructive cropping and
alignment information, and indelable copyright notification are
important features for commercial-quality stereo images IMHO.

JPEG can be used effectively for anaglyphs, but be careful about
extending that to stereo pairs.

Jon Gross


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