2001.03.07 20:12 "Problems with Photoshop TIFFs", by A. Farrel Droke

A few years ago, I wrote an OmniMark program that would find TIFF files linked to SGML documents and insert the attributes for reprowid and reprodep (width and depth) in inches. Recently, I have found that Photoshop (and a few other newer programs) build TIFFs in a new way that I cannot figure out. Hopefully, one of you can point me in the right direction.

My examples below are for Intel bit order ("II").

In the old TIFFs, I looked for the ImageWidth and ImageLength tags which would look like:

1A 01 05 00 01 00 00 00 F2 00 00 00
1B 01 05 00 01 00 00 00 FA 00 00 00

where the F2 and the FA were hex offsets to the data. I would then go down to F2 and find:

2C 01

flip-flop that to 012C hex and, voila!, it's 300 pixels per unit!

The new files at location F2 have something like:

C0 C6 2D 00 10 27 00 00

How do I get 300 pixels per unit out of that? Is this another offset or what?

Any help would be deeply appreciated!


A. Farrel Droke, PE
Corporate Director - Engineering
1601 S.E. 66th Street
Oklahoma City, OK 73149
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