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TIFF and Colour Profiles

Dierk Haasis

pro member
Recently I happened upon some problems with Vuescan-created TIFFs, which made me aware of something I've always seen as a given:

When I opened the 16-bit, ProPhotoRGB-tagged (or embedded) TIFFs coming from Vuescan, Photoshop CS2 warns me that the file format used does not support embedded [sic] profiles. I had to re-tag the files.

Bridge and other image browsers and catalogue apps showed the original files in question as being in "RGB->ProPhotoRGB".

I then began to get me up-to-date about TIFF specs and couldn't find any specific mention of there being an official tag or the possibility of embedding profiles. Other sources (like Frasner/Blatner's Real World Photoshop CS2) give the impression that embedding a profile is a given. Somewhere else it was specifically mentioned that Photoshop can tag TIFFs with a profile.

What's up, does Tiff have a standard tag (or embedding) or not?
 
If you read more of the TIFF standard you will note that it supports extensions. Hence, after finding a copy of the TIFF Version 6 standard (I have not looked at it in years) I noted the date on the cover and knew the answer was very unlikely to be there.

Following this with a visit to the horses mouth ( http://www.color.org ) and a quick look around led me to the current version of the ICC specification ( http://www.color.org/icc_specs2.html ). Searching that for TIFF yields:

The International Color Consortium has been assigned a private TIFF tag for purposes of embedding ICC device profiles within TIFF image files. This is not a required TIFF tag, and Baseline TIFF readers are not currently required to read it. It is, however, strongly recommended that this tag be honored.

- Annex B.4, page 69 (page 83 of PDF file) in:
Specification ICC.1:2004-10 (Profile version 4.2.0.0)http://www.color.org/ICC1V42.pdf
http://www.color.org/ICC1V42.pdf
And hopefully that should be enough to get you going.

enjoy,

Sean
 

Dierk Haasis

pro member
Yes, that clears one part of the equation, TIFF does support profiles (embedded or as tag).

After encountering some other problems with PSCS2 I deleted, upon recommendation, its preferences file. That brought me and all the TIFF files back into the game again.

I will not fall into a rant, especially not for such a complex program as Photoshop, but I wonder how easily its settings are corrupting the application. I didn't even have that much preference changes ...
 
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