Editing ICC profiles

[tomczak]

Is there a way/tool that would allow me to edit an existing ICC profile (e.g. change it's gamma description/import a gamma description from another profile)?

(I thought that profiles were text files, but they don't seem to be...)

[jsachs]

I don't know of any low-level editing tools - profiles are binary files. You can use the following to dump the contents of existing profiles:

http://www.color.org/profdump.xalter

I ended up having to write programs to generate profiles with particular gamma values, primaries and white points.

[David_B]

The ICC Profile Inspector from www.color.org will export and import the gamma tag as a text file and it will also edit some other tags.

You can create your own gamma curve and import it, but it must be the same size and format as the existing profile already has.

ICC profiles are not properly validated and often contain format errors even though they still work. But I had one which would export the gamma tag but would not re-import the same tag. The reason was a mismatch between the tag size in the tag list and the tag size in the tag header.

You can change the profile type e.g. mntr scnr using a hex editor

[tomczak]

Many Thanks!

I've experimented with Bruce RGB working space, but with the gammas replaced with the ones taken off the sRGB. It seems to work fine with the LightJet/DurstLambdas. I tried 3 actual profiles from labs in Vancouver, Warsaw and Bangkok, and they all blocked deepest shadows when converted to from AdobeRGB. When the modified Bruce RGB is used and then the file converted to one of the printers profiles, the blocking is cured or nearly cured (in theory - I haven't printed anything yet).