Some ICC profile questions


Some ICC profile questions:
 5 or 6 years ago, because of some issues with version 4 profiles and Photoshop, I started making V2 profiles, and have continued to make all my printer profiles as V2 up to now. (FWIW, I use the i1 Photo 2 Pro, and about 2K  patches.)  Yesterday, however, I decided to re-cal and re-profile my monitor and did it as V4. Looks fine.  
 (here's why V4:
 However, I now have almost 2 dozen color icc printer profiles in v2 format.
 So  two questions arise:
 are there consequences to using a v4 monitor profile and v2 printer/paper profiles? Judging by the pdf referenced above, the answer is "it's likely" if I'm reading it correctly, but I thought someone here might have some real-world experience in this. (My guess is that a mix of V4 and V2 "breaks" the benefits of V4 during output.)
 Which then posits the second question: 
  is it possible to convert v2 profiles into v4?
  (I'm afraid I know the answer to this one, unfortunately. I turned to ColorThink, and could not find a "convert" command. Maybe there's other specialized software that can do it? I'm on a Mac.)
If no one knows, I'll just bit the bullet, and recreate my printer/paper profiles as V4, and let you know what I find. If, after I do the first one, it appears there is enough difference to justify it, I'll remake the others  (altho I'd much prefer to be doing other things for the next several days...  ;-)
At least I don't have to deal with v2 vs v4 with my Piezography curves!
Thoughts? Comments? 
Tracy Valleau, moderator


So, I'll answer myself...
...and if I'd thought about it a bit more, I'd have been able to answer #1. If my understanding of how profiles work is correct, it would have been obvious. The both profiles are created as a comparison to the profile connection space, but when the conversion is run, the pcs is removed from the equation, and the translation is direct from the monitor to the printer. Changing either one of them will throw that direct connection out of sync.

And indeed it did, and very obviously. In my quick test, the reds all became more orange; orange became more yellow, and so on.

So: I do indeed need to redo the paper profiles. (Sigh.)

V4 vs V2:  ColorThink shows a 1% greater gamut volume on the monitor; and almost 10% greater on the paper.

All of this is of course limited to just my one particular test, but I point it out to note that the distinction between v2 and v4 is real and visible.

Tracy Valleau, moderator