Re: [Lcms-user] Getting the profile whitepoint

[Richard H. <hug...@gm...>]

On 22 November 2012 22:38, Marti Maria <mar...@li...> wrote:
> - use cmsSetAdaptationState(0) prior transform. This is very important in
> order to get the white point from CHAD

Ahh, this is the bit I didn't know about.

> Hope that works to you

Using cmsCreateExtendedTransform allows me to do this without setting
the global state. Thanks!

As an aside, I did wonder about the documentation for
cmsCreateExtendedTransform.

cmsCreateExtendedTransform(cmsContext ContextID,
               cmsUInt32Number nProfiles, cmsHPROFILE hProfiles[],
               cmsBool  BPC[],
               cmsUInt32Number Intents[],
               cmsFloat64Number AdaptationStates[],
               cmsHPROFILE hGamutProfile,
               cmsUInt32Number nGamutPCSposition,
               cmsUInt32Number InputFormat,
               cmsUInt32Number OutputFormat,
               cmsUInt32Number dwFlags);

What I expected was nProfiles = 2, hProfiles[2], BPC[2], Intents[1],
AdaptationStates[2], i.e. you set (nProfiles-1) worth of transform
data. If you do this it doesn't work, and so I have to do something
odd like:

    cmsUInt32Number intents[2] = { INTENT_ABSOLUTE_COLORIMETRIC,
                       INTENT_ABSOLUTE_COLORIMETRIC };

Also I don't think BPC makes sense for absolute-colorimetric, and I
kinda expected to be able to pass NULL there. If you do that it blows
up :)

Richard