P3D Re: JPS format images

[jon siragusa <siragusa@xxxxxxxx>]

Brian Reynolds wrote:
>
>This runs into a (non-stereo) pet peeve of mine.  Has whoever created
>the JPS *proposal* submitted it to the JPEG standards committee (or
>any of the other relevant committees, perhaps the W3 Consortium) and
>had it approved as part of the JPEG standard?  Just because a company
>comes up with a product that uses a new file format does not make that
>file format a standard.  Standards must be openly available and openly
>agreed upon.  (Yuck!  I hate the word "open" since the marketdriods
>started abusing it.)
>

No, the JPS information has not been submitted to the JPEG standards
committee.  JPS is not really a new image format.  As you know its
simply an extension of JPEG (an extension of which the JPEG committee
probably wouldn't care about).  However, the JPEG standard clearly 
defines user defined fields (called markers) by which a 3rd party can 
store information. This is where the Stereo Descriptor is stored.  
Adobe Photoshop stores some of its information in a marker when it 
saves a JPEG.

The documentation for the Stereoscopic Descriptor is freely (can't 
exactly say that for the JPEG spec.) downloadable from:

        http://www.vrex.com/developer/sterdesc.zip

While the specifications for the Descriptor were not openly discussed,
they were discussed with people from VRex, NuVision, Stereographics
and Chasm Graphics (i.e. a group quite knowledgable with respects to
digital 3D).  What resulted is a specification that is quite general
(perhaps too general?) and does the job with room to expand to any 
future needs.  If, after reading the Stereoscopic Descriptor spec,
you feel there is something that should be changed or added please let
know via private email.

>
>Until this [open standards] happens I don't think we'll ever see JPS
> support on other platforms, or in mainstream (e.g., Photoshop) software.
>

There is nothing stopping anyone who is knowledgable in any programming
language to write a JPS reader/writer for other platforms.  JPEG is
a cross-platform file format.  The Stereoscopic Descriptor, being 
basically a set of flags, is cross-platform.  There is no "standard" 
for an anaglyph or interleaved JPEG is there?  


>
>By the way, another pet peeve of mine is assuming that you can
>determine file type by examining the filename.  Unfortunately this is
>another problem popularized by Wintel.

>

Me too.  Which is why DepthCharge looks at the header info of any
file it tries to open to determine the filetype.  However, as i'm
sure you know, in order to give Windows users the ability to double 
click to open the file you need to commit to some sort of extension.

Hope this helps,
jon


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