P3D Re: JPG and destruction

[Larry Berlin <lberlin@xxxxxxxxx>]

>Date: Wed, 22 Apr 1998
>From: Ole Hansen <oha@xxxxxxxxxx>
>....................
>> Lossy compression affected the quality of 3-D image pairs less than
>> that of 2-D images of the same scene....
>
>So much for chineese science. Anyone wanting to see the destructive
>habits of JPG to stereograms (anaglyphs) are invited to visit:
>http://hjem.get2net.dk/stereoskopklubben
>
>The ghosting you see there on the JPG's is not present in the original
>PNG anaglyphs. Is there a browser where you can import PNG ?
>I will not use the stereovariant JPS if it can be avoided, because it
>has the same problem, allthough not so grave viewed with DepthCharge.
>By the way - where can we (Stereoskopklubben) get the proper red/cyan
>glasses ? That is glasses with filters matching a modern monitor ?
>regards - Ole Hansen - olehansen@xxxxxxxxx
>

****   There is at least one, and maybe several plug-ins available that
allows browsers to access PNG files. I've seen it on several download sites
and it's free.

As to the loss factors in JPG and JPS, it's there, so don't use high
compression levels. On lower compression levels it's very hard to impossible
to tell any difference (in LCS viewing) between the JPS/JPG and the original
PNG/TGA files. If I turn up the compression, the quality does visibly
degrade. Just use common sense when using JPG formats. JPG used carefully
compresses farther than PNG files, so if bandwidth is a concern, stick with
JPS for internet use. If you like quality go with PNG, though be aware that
fewer persons have the plug-in for PNG images. The usage of PNG is
increasing as it's a very good file format.

I use mostly PNG, TGA, and TIF files at home, but JPS/JPG is the easiest and
most compact for use on the internet. JPS so far is the only file type that
the stereoscopic plug-ins recognize. I'm sure they could be upgraded to
include PNG or PNS eventually.

Larry Berlin

Email: lberlin@xxxxxxxxx
http://www.sonic.net/~lberlin/
http://3dzine.simplenet.com/


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