Re: MNG/JNG specification updates

Version 0.94.9 of the APG format that I'm working on addresses sTER.  It
allows the PNG sTER-type modes plus it allows pairs of separate images to
be identified as stereo pairs.  I wasn't aware of JPS until now; I think we
did discuss allowing over-under pairs and interlaced pairs during the sTER
chunk discussions, but if so they did not make it into our sTER chunk spec.

Glenn

On Sat, Oct 10, 2015 at 5:40 PM, John Bowler <
[email protected]> wrote:

> cd src/libpngOn Sat, Oct 10, 2015 at 11:19 AM, Adeluc <png-8CwYj0sA/[email protected]>
> wrote:
> > When I create the "Stereo Image Maker v2.0.10 Alpha" freeware software to
> > demonstrate the possibilities of the "sTER" chunk, I wanted to include an
> > import JPS feature.  So I made some searches to get the file format
> > specifications.  A JPS file is essentially a JPG file with a "Stereo
> > Descriptor".  This "Stereo Descriptor" as the JPS extension has been
> created
> > by the (no more existing) "VRex Inc" company that was selling affordable
> 3D
> > helmet.
>
> If sTER is permitted in a JNG this introduces the possibility of
> conflicting information; sTER can only do a small subset of the JPG
> APP3 marker.
>
> On the other hand it is a lot easier to add sTER when adding an alpha
> channel to a JPEG than it is to insert an APP3 marker and certainly
> the images by Theo Prins that I found don't have the JPS marker in
> them; they were produced using PhotoShop.
>
> I guess the reasonable thing to do is to say that sTER takes
> precedence over the JPS information if it exists, since it's in the
> container of the JPEG.
>
> --
> John Bowler <[email protected]>
> +1 (541) 450-9885
> PO BOX 3151
> KERBY OR 97531-3151
> USA
>
>
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