[argyllcms] Re: Patching profiles with non-D50 illuminants for Absolute Colorimetric

Roger Breton wrote: 
Just to make sure I follow the arguments here, is the adaptation required
strictly when the colorimetry of the measurements is calculated for
something *other* than D50? Let's say I measure the color patches using
D50/2 then, there is no adaptation required, right? But if I measure the
color patches using A/2 or D65/2 then, what I understand the v4 spec says is
that the media white still needs to be encoded in D50/2. Therefore, the only
way to go from A/2 or D65/2, for instance, to D50/2 is through a chromatic
adaptation like Bradford.


Yes, this seems to be the case. Argyll is still pre-V4, and pre-V4 didn't
really have a way of dealing with profiles intended for non-D50
environments (apart from simply discarding this information).

I'm not convinced that this is much of a problem though.
Under what circumstances does one deliberately create a profile
with absolute measurements made under non-D50, and then want to
use the profile in absolute mode as if it had been measured under D50 ?
Why not simply create a profile that has absolute mode that
has been measured under D50, if that's how you want to use it ?

Graeme Gill.

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