I agree, BetaRGB is also D50, which I like versus the D65s. I'll check out eciRGB... That's not one I'm familiar with. Thanks for the suggestion. - Brad > On Jul 7, 2014, at 3:13 PM, Roger Breton <graxx@xxxxxxxxxxxx> wrote: > > Also, what I like about eciRGB is the fact there is never any issues with > chromatic adaption since everything happens on a pure-D50 scale, from PCS to > RGB to XYZ to "infinite and beyond!" -- sorry, got carried away... > > / Roger > > -----Original Message----- > From: argyllcms-bounce@xxxxxxxxxxxxx [mailto:argyllcms-bounce@xxxxxxxxxxxxx] > On Behalf Of Brad Funkhouser > Sent: 7 juillet 2014 14:40 > To: argyllcms@xxxxxxxxxxxxx > Subject: [argyllcms] Re: Custom Illuminant > > > When AdobeRGB is a little too small, and ProPhotoRGB is just too big, try > Bruce Lindbloom's BetaRGB, it might be just right. > > - Brad > > >> On Jul 7, 2014, at 9:18 AM, <robert@xxxxxxxxxxxxxxxxxx> wrote: >> >> << How does the gamut mapping know that no mapping is required ? If >> you tell it the source gamut is ProPhoto, then it will think that lots >> of gamut mapping is needed, since the ProPhoto gamut is so much larger >> than a printer !>> >> >> Well that has finally clarified that point for me! So with Perceptual >> the whole source gamut is squashed down to the destination gamut, even >> if all the colors are within the destination gamut. This means that >> in a Perceptual mapping from ProPhoto to print, colors will be >> compressed resulting in desaturation of the image, particularly of the >> more saturated colors nearer the print gamut boundary. >> >> So the following strategy might make sense for a Relative intent > conversion: >> - Going from ProPhoto to print, make sure the colors are more or less >> within the destination space to avoid too much clipping. >> >> And the following for Perceptual: >> - Do a Relative conversion from ProPhoto to AdobeRGB (making sure the >> colors are more or less within the AdobeRGB space before the >> conversion to avoid too much clipping). >> - Do a Perceptual mapping from AdobeRGB to print. >> >> I did a comparison of a 1-step ProPhoto [Perceptual to Print >> conversion] with a 2-step [ProPhoto to AdobeRGB conversion, followed >> by an AdobeRGB Perceptual to print conversion]: >> - If the original image colors are all within the AdobeRGB gamut there >> is quite a difference if the print gamut is much smaller than >> AdobeRGB, but none if it is of similar size. >> - If the original image colors are outside the AdobeRGB gamut, the >> 2-step approach is significantly better even if the print gamut is >> very close to the AdobeRGB gamut. >> This is a bit puzzling because I would have expected a difference in >> all cases (if the full ProPhoto gamut is squashed down in a Perceptual >> conversion). >> >> What would be nice would be to be able to make the smaller >> intermediate working color space using tiffgamut/colprof (from a range >> of typical images), but I don't see how that could be done. >> >> Robert > >