This might help:
Frankly, the last thing you want to do is be in charge of a CMYK conversion if you're not provided the exact recipe for the press output! There is no such thing as a 'straight conversion' every device requires a different recipe of CMYK and the incorrect recipe can produce real headache’s on press.
Neutral (gray or BW) areas of shot (i.e., neutral elements on jewellery , or neutral
backgrounds) to have UCR/GCR (3 color removal) applied specifically so that
color does not swing on press.
means in my opinion: remove as much of equal amounts C,M,Y and replace by K in order
to stabilize the print and to reduce the ink percentage. That's called UCR if done only
in neutral areas and GCR if done everywhere. GCR comes light, medium and heavy.
A 'straightforward conversion" according to the recommendations of the printing people,
using an ICC profile which is appropriate for the process and the paper, is absolutely correct,
for instance SWOP or ISOCoated-v2-eci. The specific GCR belongs as part of the process
to the profile.
I read as well the inquiry in the Photoshop Forum. In my opinion it's clearly a misunder-
standing, that neutral areas should be printed by K-only. It would be nonsensical, because
K-only cannot create neutral D50 gray on arbitrary paper. Furtheron the transitions between
neutral areas and almost neutral areas would be very wrong.
Best regards --Gernot Hoffmann
In my opinion it's clearly a misunderstanding, that neutral areas should be printed by K-only.
Yes, I'm fully aware of that, and I assumed my initial reply made that clear. It was merely an "emergency workaround".
Anyway, thanks for confirming, and so I think there is a consensus. With the correct profile the request makes little sense.
I have posted back in the photshop forum too.
Essentially, the client took control of this process and i just handed them masks for each image.
Like you say, I assume theyhave simple removed equal amounts fo C,M,Y on the GRACol file.
I rached out to quite a few people regrading this and its seems everyone had the same conclusion which was "a pointless exercise"
The client, however felt this was necessary for the project.