ISO 12647 unity profiles
ISO 12647 unity profiles
- Subject: ISO 12647 unity profiles
- From: Henrik Holmegaard <email@hidden>
- Date: Wed, 31 Oct 2001 08:57:39 +0100
"Broudy, David" <email@hidden> wrote:
there aren't any applications I know of that even look at the colorsync
control panel so it really doesn't matter how you set it up, unless there's
some mystery app out there that uses it
Well, Photoshop 5.0, 5.5 and 6.0, Illustrator 9, Acrobat 5 and
Linocolor 6 are examples of applications that all look to the System
Profile functionality in ColorSync 2.5 and 2.6, and the Display
Profile functionality in ColorSync 3.0.
This functionality is controlled through the ColorSync control panel
and the Monitors control panel, though in different ways for
ColorSync 2.5 and 2.6 versus for ColorSync 3.0.
For every data object the Apple ICC API also requires a source ICC
format profile. This is a basic feature of CIE workflows, whether
PostScript or ICC, you can't convert unless you can first present the
data to the intermediate color space, XYZ or Lab.
This means that the Apple ICC API requires a default source profile
for CMYK, RGB, Grayscale, Lab, XYZ and Lab. These are technically
called unity profiles, because technically they are supposed to do
nothing. This isn't quite true as only the Lab and XYZ profiles are
effect-neutral. Using the CMYK, RGB and Grayscale means using some
rather horrenduous source color spaces.
Apple's underlying problem is that the unity profiles are technically
necessary, so it has been hunting for a functionality to place on top
of this necessity which proves confusing and inscrutable to users,
though in fact it is simple and clear once you know what is going on.
Apple's solution has been the ColorSync Workflow concept, which first
appeared with ColorSync 2.5. The solution is functional and helpful
for users, if it is properly implemented and properly documented.
Prior to the June meeting of the ICC, I suggested that Apple make the
CMYK unity profile a standards-based one by building on ISO 12647-2
as Adobe already does. The RGB unity profile should have enough gamut
volume for RGB input to support the ISO 12647-2 gamuts for output.
Otherwise, if as a user you point application software to the
ColorSync Workflow option, and you leave the unity profiles in place,
you will get undesirable results.
Over the summer there were examples on the ColorSync Users List where
users applied the device unity profiles for production leading to
undesirable results and undesirable user experiences.
Surely, this can't be the point -:)