Mike, this is the expected behaviour.
You say you want to separate in two transforms, and
that's ok, you can either use
CMYK -> [GraCol + Gracol] -> CMYK -> [Linearization]
or
CMYK -> [Gracol + Lab] -> Lab -> [Lab -> GraCol + Linearization]
Both are valid, but you cannot use CMYK as middle space in the
second way. Also you need Lab identities on both sides.
I guess what you really want is an input/output transform first
and after that a second transform with the linearization.
To create a transform that with only one devicelink you can use
cmsCreateTransform(tonalProfile, TYPE_CMYK_8, NULL, TYPE_CMYK_8, 0, 0)
Hope this helps
Marti
Quoting Mike Marcoe <marcoe.m...@gmail.com>:
> I have a CMYK->CMYK profile that I've chained with a device link profile to
> apply tonal correction to the image. This works as expected. I now want to
> separate this into 2 passes and I find that making 2 transforms does not
> work. I get an Invalid PCS error from cmsCreateTransform. The PCS is invalid
> because it is CMYK and cmsCreateTransform is expecting Lab or XYZ.
>
> Here is some code that shows the problem.
>
> int main (int argc, const char * argv[]) {
>
> LPGAMMATABLE transferFunctions[4];
>
> // load a stock CMYK profile (this is distributed with Photoshop but
> anyone should do)
> cmsHPROFILE hInProfile = cmsOpenProfileFromFile("CoatedGRACoL2006.icc",
> "r");
>
> // build a linear gamma table (my app doesn't use linear but it doesn't
> matter in this example)
> const int numberOfEntries = 255;
> transferFunctions[0] = cmsBuildGamma(numberOfEntries, 1.0);
> transferFunctions[1] = cmsBuildGamma(numberOfEntries, 1.0);
> transferFunctions[2] = cmsBuildGamma(numberOfEntries, 1.0);
> transferFunctions[3] = cmsBuildGamma(numberOfEntries, 1.0);
>
> cmsHPROFILE tonalProfile =
> cmsCreateLinearizationDeviceLink(icSigCmykData, transferFunctions);
>
> // build the chain of profile, first xform is CMYK->CMYK, second xform
> // is CMYK->CMYK with the above transfer function
> cmsHPROFILE profiles[3];
>
> profiles[0] = hInProfile;
> profiles[1] = hInProfile;
> profiles[2] = tonalProfile;
>
> int intent = INTENT_ABSOLUTE_COLORIMETRIC;
> int flags = cmsFLAGS_NOTPRECALC | cmsFLAGS_HIGHRESPRECALC |
> cmsFLAGS_NOPRELINEARIZATION;
>
> // this succeeds
> cmsHTRANSFORM chainedTrans = cmsCreateMultiprofileTransform(profiles, 3,
> TYPE_CMYK_8, TYPE_CMYK_8, intent, flags);
>
> // but doing it twice fails.
> // The second transform is not built because of an invalid PCS
> //
>
> // passes
> cmsHTRANSFORM trans1 = cmsCreateTransform(hInProfile, TYPE_CMYK_8,
> hInProfile, TYPE_CMYK_8, intent, flags);
>
> // fails
> cmsHTRANSFORM trans2 = cmsCreateTransform(hInProfile, TYPE_CMYK_8,
> tonalProfile, TYPE_CMYK_8, intent, flags);
>
> }
>
> How can I separate these steps? Thank you.
>
------------------------------------------------------------------------------
Start uncovering the many advantages of virtual appliances
and start using them to simplify application deployment and
accelerate your shift to cloud computing.
http://p.sf.net/sfu/novell-sfdev2dev
_______________________________________________
Lcms-user mailing list
Lcms-user@lists.sourceforge.net
https://lists.sourceforge.net/lists/listinfo/lcms-user
