[argyllcms] Re: How can I tell if I'm using my profile? (and other questions)

Adrian Mariano wrote:
I ran dispcal with the -o option so as to produce a profile as output. I loaded the profile using dispwin under linux. Now I go into firefox 3 and color management is turned on. Does firefox find the profile that was loaded using dispwin?
You can test if Firefox 3 uses your installed display profile by temporarily installing a profile with swapped colors, like this one: 
http://hoech.net/files/BRG.icc
Close your browser, install the above profile using dispwin -I BRG.icc
Open your browser and visit http://www.color.org/version4html.xalter
The big image should have magenta-red sky and green mountains, and look like the topmost small image, if the display profile is used.
Can I observe the effects of this profile? (Am I likely to be able to see the difference between using the profile vs. just calibrating the display and not using the profile?) As a second set of questions: my goal is simply to get colors to look "right" (good) in pictures I take with my digital camera or if I visit a web page and look at pictures of colorful merchandise, for example.
Depends. Most of the images on the web are "unprofiled" (do not contain an embedded profile), so any differences you see in those cases will only be because of calibration.
I made the above profile using sRGB, but I noticed the suggestion in the documentation that perhaps a gamma of 2.4 would be a better choice? I think the last time I ran a calibration I specified a temperature of 6500 K, but this time I forgot that option, which apparently means the monitor's native white point is used. Am I better off using the native white point?
Again, depends. Most (LCD) monitors offer white point control only by adjusting their internal LUT curves to reach the target value, thus sacrificing some of the 256 possible levels per channel and introducing the danger of visible banding in gradients (at 8 bit, some more expensive displays also haver 10 or 12 bit internal LUTs). So yes, it might be better to use the native white point. A gamma of 2.4 is a good starting point, you could also use dispcal -R to get a measurement of your uncalibrated displays approximate gamma response and then use that.
How long should I expect it to take for my LCD display to stabilize? I sat down and woke it up and started looking at its brightness and it was 130 cd/m^2. I couldn't remember what I'd calibrated it to, but I new it was much higher, something more like 170 cd/m^2, I think. I sat in dispcal and watched the value creep upwards. After, oh, maybe 45 minutes it seemed somewhat stable at 166 cd/m^2, though it might have been drifting a bit still. I assume that trying to run a calibration or a profile while your display is drifting is going to give a poor result.
Yes, every display technology needs a certain warm-up time. The 45 minutes you mentioned seem very reasonable. I tend to wait about an hour before calibrating/profiling displays. 

Regards,

Florian

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