Hi, >One thing I still can't seem to answer one way or the other is given I >have a profile embedded in an image that says what the white point is, >will an app (Photoshop) display "white" as what the embedded profile >says or what ever the display profile says?
At first, white point is only used on absolute colorimetric intents. All remaining intents does assume observer is totally adapted to the destination media white. So, using perceptual or saturation intents, source device white will be mapped to destination device white. That is, a rgb of 255, 255, 255 will (or should be) always mapped to 255, 255, 255 Then comes the absolute colorimetric intent. The purpose of this intent is to reproduce color "as is". That means, no adaptation is done and the white point mismatch does result in a moderate to hard cast. Placing, for example, two monitors side by side, one monitor using D93 and the other using D65, will show same colors only by using absolute colorimetric intent. But of course, if the image is intended for, as example, D65, will result on a stong yellow cast in the D93 monitor. Returning to your question... you have two profiles and two white points. You can use absolute colorimetric intent to obtain same absolute colors, without any adaptation. So, in this situation the concept of white has no meaning, there is no subjective white, since there is no adaptation state. If you use the origin device white point, this will be represented as a color in the destination with little or none relationship with destination white point. So, if your embedded profile says "this image is using D65" and the monitor profile says "this monitor is using D93", a transform using perceptual, saturation or relative intents will ignore this information, and a transform using absolute colorimetric one will convert RGB of 255 255 255 to D65 and then will represent D65 chromaticity in the monitor. This is quite yellow under D93 illuminant. Regards, Marti. ----- Original Message ----- From: "James Burgess" <[EMAIL PROTECTED]> To: "Mart� Maria" <[EMAIL PROTECTED]> Cc: <[EMAIL PROTECTED]> Sent: Tuesday, July 23, 2002 11:46 PM Subject: Re: [Lcms-user] Re: Thank You One thing I still can't seem to answer one way or the other is given I have a profile embedded in an image that says what the white point is, will an app (Photoshop) display "white" as what the embedded profile says or what ever the display profile says? I have tried this in the past an have seen the display "over rule" the image (which seems wrong). On Monday, July 22, 2002, at 04:33 PM, Mart� Maria wrote: > Hi, > > With those measurement you could obtain a matrix-shaper profile. > For some authours, these works on monitor even better that > CLUT-based profiles. This is not unusual, but pretty normal indeed. > The profiler is happy with these patches, just take the > "MonitorTemplate.it8" file, in "pics" folder as a example. > On more grays, better the profile. > > lcms has a function to build "virtual" profiles based on these > settings. cmsCreateRGBProfile(). You can save the resulting > profile to disk by using _cmsSaveProfile() too. > > Regards, > Marti. > > > ----- Original Message ----- > From: "James Burgess" <[EMAIL PROTECTED]> > To: "Mart� Maria" <[EMAIL PROTECTED]>; <lcms- > [EMAIL PROTECTED]> > Sent: Monday, July 22, 2002 2:33 PM > Subject: Re: [Lcms-user] Re: Thank You > ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ Lcms-user mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/lcms-user
