Re: MNG/JNG specification updates

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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