2006.09.26 23:25 "Re: [Tiff] Status of ISO JBIG and CIELAB JPEG support", by Jean-Yves Le Ridant
Photoshop doesn't support ITULAB.
Photoshop only supports CIELAB and ICCLAB encodings in TIFF.
Yes, so you have to replace the photometric tag in tiff's directory by ICCLAB, then when loaded by Photoshop, apply a linear "level" to a and b, matching the rescale of ITULAB specif.
Never used Photoshop?
Of course there some loss against what would be a real ITULAB support.
For this test image, Photoshop see a valid ICCLAB jpegintiff structure, and considering automatic exposure of a fax, compression ratio ( not had look to quantization tables but seems like quality 20 or less, 10 Mo to 130k)... colors are "plausible", there's usuals jpeg's artefacts, but nothing you can attribute to a bad color processing.