2020.08.16 20:54 "Re: [Tiff] Problems with Photoshop when a file is written is strips", by Bob Friesenhahn

Strange, for me, tiffinfo from libtiff-4.1.0 shows the predictor tag:

TIFF Directory at offset 0x8 (8)
   Image Width: 32 Image Length: 32
   Resolution: 1, 1 (unitless)
   Bits/Sample: 16
   Sample Format: IEEE floating point
   Compression Scheme: AdobeDeflate
   Photometric Interpretation: RGB color
   Samples/Pixel: 3
   Rows/Strip: 32
   Planar Configuration: single image plane
   Predictor: floating point predictor 3 (0x3)

It turns out that it was there. I skipped the big XMP dump but there was this additional stuff at the end:

   Photoshop Data: <present>, 16332 bytes
   EXIFIFDOffset: 0x149684
   ICC Profile: <present>, 496 bytes
   Predictor: floating point predictor 3 (0x3)
TIFF Directory at offset 0x149684 (1349252)
   ColorSpace: 65535
   PixelXDimension: 429
   PixelYDimension: 640

Chris Cox's draft specification is still available at "http://chriscox.org/TIFF_TN3_Draft2.pdf". According to the license text, it appears to be mostly freely distributable.

Bob

Bob Friesenhahn
bfriesen@simple.dallas.tx.us, http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer, http://www.GraphicsMagick.org/
Public Key, http://www.simplesystems.org/users/bfriesen/public-key.txt