2004.12.07 17:16 "Re: [Tiff] Having problems adding IPTC to a TIFF", by Bob Friesenhahn

1. Tolerating bugs, for the sake of backward compatibility with bug compensating software, only leads to validating the bug. Photoshop did that, according to Chris, to compensate for the GraphicsMagic bug. Bob, building from GraphicsMagic rather then reading a spec, next tried to validate the GraphicsMagic behaviour earlier saying that Photoshop did it too. Other software, building on LibTiff, will do it too...

Photoshop 3.0 (around the time the abberant behavior is documented to first be introduced) far pre-dates GraphicsMagick. Photoshop did it to be compatable with some other existing software. I don't think that Adobe cares much about GraphicsMagick. ImageMagick/GraphicsMagick behave like Photoshop since Photoshop is the industry's de-facto standard.

4. There's some value in truth. Correcting a mistake is a good thing, even if it does come at some cost.

This mistake has existed since maybe 1992. Mistakes which have existed for a very long time are difficult to correct later.

Well maybe the first thing to do would be to see what Photoshop IS doing. Since Adobe is in charge of the TIFF specs, if they're writing IPTC as a LONG array, then THAT IS the spec, even if it's conceptually incorrect. If they're writing UNDEFINED of whatever, then libtiff should definitely follow.

Adobe did not invent IPTC in TIFF. However, as was previously mentioned, Photoshop is writing IPTC as a LONG array, although it will accept both forms.

Bob

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Bob Friesenhahn
bfriesen@simple.dallas.tx.us
http://www.simplesystems.org/users/bfriesen