[Openicc] seeking for advice on rendering intent and black point compensation

[Graeme Gill]

Alastair M. Robinson wrote:
> As for the default intent for such conversions, I would prefer either 
> Perceptual or Relative Colorimetric with BPC *ON* to be the default.  If 
> you have an image which is in a "print" colour space, its black point 
> will be much lighter than the "pure" black of an additive RGB working 
> space like sRGB - so a relative colorimetric transform from a printer 
> colour space to a working space will result in a washed out, faded look. 
>   That's the effect Black Point Compensation is designed to minimise.

The desirability of using BPC with perceptual, depends on the
profile. For instance, it would be a bad idea to use BPC
with Argyll generated profiles where the source colorspace
has been specified when generating the profile, since the
perceptual gamut transform incorporated in the profile
already does a high quality mapping of the black point.

Of course with profiles from other sources, or where a
source gamut was not specified during profile construction,
BPC may be desirable.

[ie. BPC is a grey axis only, on the fly gamut mapping.]

Graeme Gill.