Color Errors? Gamut Clipping?...Or is i1Match 3.6.3 for Snow Leopard too old?

[Tim Lookingbill]

Joe, I'm aware of fluorescent light's spiky spectra. This is not the problem. There are fluorescent lights on the market that are used quite successfully for proofing prints. Normlicht viewing booth to name one which I believe Andrew uses.

The pinkish blue appearance is not an intended nor is it healthy for eyes or a desired look to edit images on a display with. I tried it.

The i1Match software does not neutralize the rest of the gray tonal scale effectively enough to over ride the eye's adaptive characteristics into NOT seeing the pinkish blue white. Besides that there is no light source in the natural world or artificial that looks this pinkish blue. This is an error (or interpretation) by X-rite and/or Apple's integration of software driven WP appearance downloaded to the video driver. From using Apple's Calibration Utility WP slider adjust, Apple has other ideas on what 6500K should look like as well.

It doesn't matter anyway because I got the i1Match software to measure my Dell's WP at 6600K by adjusting the Dell's RGB gains which of course creates a slightly warm orangish yellow tint. How do you explain that huge jump in interpreting the color cast using the same colorimeter. According to Xrite looks like 6500K could look either pinkish blue or orangish yellow. So much for accurate colorimeters.

This guy was having even worse problems getting accurate native WP readings with his i1Display2/i1Match colorimeter system...

http://forums.dpreview.com/forums/readflat.asp?forum=1004&message=34268372&changemode=1

Reading on to the second page of that thread tells the solution which was to buy another i1Display 2 package. He should've been reimbursed by Xrite which I'm assuming he was.

[Tim Lookingbill]

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.

[Tim Lookingbill]

Correction, it doesn't matter what display profile is loaded in the system. If I convert from D50 Lab space to i1Display 6600K profile using Apple CMM/Absolute Colorimetric it doesn't show the orangish yellow cast.

However if I convert to SuperCAL's or AppleRGB or AdobeRGB or any other simple matrix 6500K WP profile it does show this cast.