Unfortunately, perceptual rendering is not available for Version 3 matrix profiles such as sRGB and ProPhotoRGB. Photoshop does allow one to select perceptual rendering, but the request is ignored and relative colorimetric rendering is performed. The matrix profiles lack the necessary look up tables for perceptual rendering.
Regards,
Bill
Hi Bill, glad I could get some input from you on this. I've discovered some other very odd behaviors with Apple's CMM driven rendering intents in Photoshop with matrix based/rendering intent limited profile conversions I wasn't aware of before.
I got to tinkering around creating a Lab Color space gradient in Photoshop CS3 to check banding with my newly made 6600K i1Display profile loaded in the system versus SuperCal's version loaded. Of course I get banding using both and noticeably different shaped 3D gamut models viewed in Colorsync utility, but that wasn't the only odd anomaly. See the attached screenshots below.
I always suspected Apple has issues with there CMM in regards to how they influence these rendering intents in Photoshop and is probably the reasons for the slight color shifts I get in highly saturated colors converting from ProPhotoRGB to sRGB even if I don't use Apple's CMM conversion engine.
The first shot is having the i1Display profile loaded in the system and choosing
Apple's CMM/Absolute Colorimetric rendering intent to convert to the loaded i1Display profile. No problems to preview. The i1Display profile has a Chromatic Adaption 'chad' ICC tag in its construct and a White Point Media Tristimulus 'wtpt' tag stated at D50. This profile was built from measuring my Dell's native WP after adjusting OSD RGB gains to get the colorimeter to read 6600K.
The second screenshot is having the SuperCal version loaded in the system and converting to it. This profile actually ends up as a simplified matrix formula profile that's read by Photoshop in "CustomRGB..." as straight HDTV Rec 709 XY coordinates including 6500K WP. It doesn't have a 'chad' tag and its 'wtpt' tag is stated at 6500K, not D50 like the i1Display's.
You'll see that Apple CMM still utilizes or deals with WP mapping in odd ways. It does this converting from D50 source space to any 6500K color space, not just my display profiles.
All this still happens even in Snow Leopard on a 2010 Mac Mini.