P3D JPG and destruction

[Ole Hansen <oha@xxxxxxxxxx>]

Jonathan Gross <jonathan.gross@xxxxxxxxxxxx> wrote:

> ....there is a big difference between the requirements for
> high quality monoscopic and stereoscopic images....
That is Right !

> ....that difference is exactly why JPEG image compression is
> not well suited to stereoscopic images, even though it works
> great on 2D images....
That is even more right !
I wonder if anyone on this list would have the trouble to see
the effect of JPG on Stereoskopklubbens updated website on:

http://hjem.get2net.dk/stereoskopklubben

I am not pleased with the destruktion of the stereograms by JPG
due to ghosting, false pixels etc, etc. as compared with PNG, but
what can I do ? All comments are appreciated.

> With stereographs, each eye sees a different image, and the
> psycho-physiological based vision system is inherently sensitive
> to the slightest differences from one to the other.
That is right, but GIF is useless with color photograps, and then
we are stuck with JPG.

> Bill Ewald, a researcher at Eastman Kodak.....
A very good description of the problem. He did not use JPG ;-)

> In fact, the visual system is far more sensitive in the horizontal
> direction than in the vertical....
Hm-hm - There is no vertikal stereo, only horizontal (unless you lay
on a couch). That is the reason for the libelle in many stereocameras.

> JPEG retains the spatial resolution of the original image....
It certainly does not !

> ....but homogenizes the colors of adjacent pixels to achieve
> high data compression ratios....
It certainly does - and destroyes (nearly) the stereogram.

> By the way, if one is going to take the time to carefully scan a
> stereo slide, why not scan it at a higher resolution that what you
> are using right now?
Because the graphic files are BIG - More than 25 Mb per stereogram
in a non-destruktive fileformat. We do have a technical problem :-[
regards - Ole Hansen - olehansen@xxxxxxxxx



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