Re: PNG roots and farewell

The current spec has an easy, completely open, provision to allow any
desired information to be added; the private chunk mechanism.

I can, and probably will, simply define a private chunk exIF, provide
a spec and implement sufficient support for my purposes.  No votes,
nothing.  If something is specified and published in an accessible way
and it it pays a small amount of respect to the actual ISO-PNG
specification it would probably stand a good chance of being adopted
unchanged, if, indeed, that was even necessary.  I note that ISO-JPEG
does not seem to have adopted EXIF, rather there is a JPEG definition
of how to make "private" APPn markers.  CIPA used that; EXIF in JPEG
is done by a private marker.

As for APNG, well, it was really easy to do that in a way that
conformed to ISO-PNG and required no approval; it just required a
private critical chunk, say ApNG, but no, that didn't happen.  Chris
is the first person I've heard to state it is alive; I heard recently
from an insider that the industry proponent had pretty much dropped
it, and I can tell that *animated* GIF is still very much alive.  I
like animated GIF; it is a simple, powerful and just works, I can
re-implement it in PNG if I want, I just need the AgIF chunk.

This comes back to the thing about standardization; a standard is
meant to unify industry practice when that practice has stabilized.
The standard resolves differences between competing specifications and
the result is written up in the approved standard language.  Nothing
more; no invention, no creation of wonderful new features, no cutting
competitors out of the marker, just standardization.

So we could do that with EXIF.  All we have to do is decide the case
of the final byte.  There really is no need to say anything that CIPA
has not already said.  But, while I understand all the contributors to
this thread who feel frustrated (I do myself), the bottom line is that
the only existing PNG based implementation is that zTXt chunk.  I
would vote *for* formal adoption of those keywords (Exif *and* XMP
and, indeed, the general exif: extension); I think the implementation
sucks, but then I think SAE bolts suck yet I would accept them every
day over Whitworth:

http://www.nemgtr.org/53-news/tech-topics/330-whitworth-metric-sae.html

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

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