Re: MNG/JNG specification updates

John Bowler <[email protected]>
Newsgroups gmane.comp.graphics.png.general
Message-ID <CAP7U399sqa39H1MMHUbWh-XNhqYspaEaGSNDDGjSTyRdwDDviw@mail.gmail.com>
On Sat, Oct 10, 2015 at 5:47 PM, Adeluc <png-8CwYj0sA/[email protected]> wrote:

I agree; sTER overrides any information in the JPEG.

I think if the decoder interprets APP markers in the JPEG and does
something specific to the APP markers with the resultant image that's
probably OK too and I don't think that can be prevented.  Another
example would be using the ICC profile from the JPEG.  Perhaps the JNG
spec should say something about conflicting APP markers.

The issue has already been resolved with respect to color spaces,
though only by implication; the JNG spec *requires* JFIF data (which
uses the CCIR 601 color space) but it *permits* cHRM and iCCP.  The
implication is that the JFIF color space is overridden if cHRM or iCCP
is present.  (The same issue exists with the gamma encoding, but JFIF
had already stated that the gamma encoding was arbitrary).

-- 
John Bowler <[email protected]>
+1 (541) 450-9885
PO BOX 3151
KERBY OR 97531-3151
USA

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