Datacolor User to User Support Group.

In a message dated 4/28/06 11:11:07 AM, martin@... writes:


> 
> That's interesting but a bit confusing... How come the ICC profile
> created by Spyder managed to adjust the color temperature on the 3007
> (which doesn't have any RGB adjustments) if only the gray balance is
> handled by the profile?
> 
White is a gray too... gray balance and whitepoint (which is white balance) 
are both controlled at the videocard level, where they effect everything on 
screen, not just application windows that use the monitor profile.

>  What is the use of a color profile assigned to
> a monitor under Windows when it actually only is a gray profile?
> 
The use of assigning a monitor profile under Windows, is that color managed 
applications call on Windows to provide this monitor profile to them so that 
they can use it. Windows itself doen't use the profile but as noted above, it, 
and everything else on screen, is corrected at the video card level (this isn't 
a gray profile, its a set of video card corrections). So there is two levels 
of color correction produced by the Spyder (or other monitor calibrators): 
video card corrections that control the gamma, whitepoint and gray balance 
globally, to everything on screen, and the profile, which color managed apps apply 
to correct the color.
> 
> What's the point of assigning a profile to a monitor if it doesn't
> really do anything with the colors?
> 
It does do things to colors, in any application that chooses to utilize color 
management... Browsers on the Mac, for instance, are color managed; while 
browsers on Windows are not. 

>  How come there still is a
> perceptual color difference when using the profile?
> 
You aren't using the profile at the Windows desktop level. I suspect that 
shooting a screenshot of that desktop color, and opening two copies of it in 
Photoshop, on two calibrated monitors, will show the same blue on both, while the 
desktops will continue to be mismatched. That is, unless one of the monitors 
can't reach that blue... in which case its a gamut limit problem, not a color 
profile problem (or an OS limitation problem...)
> 
> Where should I apply the created profiles? In Photoshop but not in
> Windows?
> 
Most modern color managed apps do this automatically, so there is seldom a 
need to apply monitor profiles yourself anymore... either the app does it for 
you, or it can't be done, not too many manual application cases anymore.

>  When I configure ACDSee to use the profile for output,
> there's no visible difference when the profile is also assigned to the
> monitor, so why not just assign it to the monitor?
> 
I'm not an ACDSee user, so I can't tell you what settings to use, or even 
what workflows you are describing... or what level of color management ACDSee 
uses. Someone else can probably answer that.
> 
> Very confusing and unnecessary complicated! 
> 
Automatic profile application is   not unnecessarily complicated. Having the 
OS not use it may be inconvenient, and not knowing where profiles are in use, 
and where they are not is certainly confusing. But none of this can be blamed 
on monitor calibration products, they do what they can, and are restricted by 
OS and application limits. Complain to Bill Gates. Actually, I suspect he'd 
tell you that Vista will fix this all, and save the world in the process.

> The correct way would be
> to create and assign one profile for each input/output device and
> that's all.
> 
Thats what Windows does; which has the following problems: A dual head video 
card controls two monitors, but is considered one device by Windows... oops... 
and a printer might need a different profile for each paper, or other 
variables, like which black ink is in use, and a Windows assigned single device 
profile won't be of much use here! Oh, and while Windows assigned a profile to your 
monitor, it does not actually use it in any way, so OS level color is not 
profile corrected.

>  Programs should then not need to use any profiles, because
> the colors would be handled correctly by the input/output devices
> anyway...
> 
Trust Windows to manage all your color for you! I've heard that one before. 
Windows98 allowed you to assign a custom printer profile to a printer, but it 
then went and used the canned profile instead, and didn't bother to mention 
this to you. And Windows used to assume sRGB as a source space instead of 
honoring the profile tag. Thats why companies like Adobe don't use Windows (or even 
Mac) color management for anything but asking what the monitor profiles are; 
after that they do all their own color conversion at the application level. And 
all serious color work is done using these application level color 
conversions, not OS level ones.
> 
> Furthermore: I've read reviwes of the Gretag MacBeth products on the
> internet where users claim they were able to match different monitors
> to produce the same colors (screenshots proove that, btw). Why is that
> possible with the GMB product, but not with the ColorVision's?
> 
> Both products work the same way, and follow the same restrictions. Feel free 
to buy a Gretag monitor calibrator, and complain to them about these issues.

C. David Tobie
Product Technology Manager
ColorVision Business Unit
Datacolor Inc.
CDTobie@...
www.colorvision.com