P3D Re: JPG and destruction

[jon siragusa <siragusa@xxxxxxxxx>]

>
>Date: Mon, 20 Apr 1998 01:06:27 -0400
>From: roberts@xxxxxxxxxxxxxxxxx (John W Roberts)
>
>>Date: Sun, 19 Apr 1998 18:09:07 -0600
>>From: Ole Hansen <oha@xxxxxxxxxx>
>>Subject: P3D JPG and destruction
>
>>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.
>
>Does JPS address this issue? (For instance, using rules to process both
>images together in a coordinated manner to facilitate 3D?)
>

No.  I don't know enough of the gory details of JPEG compression to
even know if its possible to tweak a JPEG compression algorithm to
be "stereo-friendly".  The very nature of JPEG compression is not 
ideal for stereoscopic images so i would think that tweaking the
algorithm to make it "stereo-friendly" would defeat the benefits
of JPEG compression.

Also remember that all JPEG compressors are not created equal!
We have found that quality and file size vary from compressor
to compressor.  Try out a few different programs and see which
ones give you the best results at the highest quality setting. 

In my opinion and rough testings, a JPG/JPS that is compressed 
with a high quality setting is almost indistinguishable from 
the original and is perfectly fine for most applications.

For archival and certain other cases where you need absolute
maximum image quality or your content is not otherwise suited 
for JPEG compression, i would recommend PNG/PNS.

A while back i had compiled a small JPS vs. PNS test suite (in HTML
with DepthCharge).  I never actually finished it, but if there is 
enough interest (email me off list) i'll clean it up and put it
online for you to check out.

jon




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