Re: fundamental question - monitor profile as working RGB?
Re: fundamental question - monitor profile as working RGB?
- Subject: Re: fundamental question - monitor profile as working RGB?
- From: Graeme Gill <email@hidden>
- Date: Wed, 10 Dec 2003 22:31:25 +1100
Chris Murphy wrote:
It is easily verifiable. Create an RGB black to white gradient in
Photoshop, set the info palette to display RGB and LAB simultaneously,
move your cursor around. a*=0, b*=0. If yours doesn't, please send me
your display profile and let me know what created it because that's what
I'm looking for.
No need for all that:
icclu -ff -ir Hitachi2112.icm:
0.000000 0.000000 0.000000 [RGB] -> Lut -> 1.469890 -4.363155 0.037092 [Lab]
0.100000 0.100000 0.100000 [RGB] -> Lut -> 2.733917 -0.312825 -4.317044 [Lab]
0.200000 0.200000 0.200000 [RGB] -> Lut -> 8.801940 4.170964 -6.267672 [Lab]
0.300000 0.300000 0.300000 [RGB] -> Lut -> 21.012962 5.083687 -6.003064 [Lab]
0.400000 0.400000 0.400000 [RGB] -> Lut -> 34.688901 4.026814 -4.677926 [Lab]
0.500000 0.500000 0.500000 [RGB] -> Lut -> 47.491235 2.699885 -3.467332 [Lab]
0.600000 0.600000 0.600000 [RGB] -> Lut -> 59.496969 1.590981 -2.465567 [Lab]
0.700000 0.700000 0.700000 [RGB] -> Lut -> 70.823172 1.019447 -1.762812 [Lab]
0.800000 0.800000 0.800000 [RGB] -> Lut -> 80.710138 1.372527 -1.218513 [Lab]
0.900000 0.900000 0.900000 [RGB] -> Lut -> 90.625619 0.639139 -0.023024 [Lab]
1.000000 1.000000 1.000000 [RGB] -> Lut -> 100.000000 -0.001952 -0.001952 [Lab]
I created the profile with Argyll (of course!), and no, I haven't used
a display calibration utility, the above is the native response of
my monitor, with whatever settings it currently has. I'll email
you the above profile separately.
No it doesn't. Profiles contain more information that that which could
be used for determining the gray balance of a display.
Sorry, I'm not following the above statement. The point I'm trying to make
is that it is not robust, nor are there any algorithmic advantages that I'm
aware of, in designing a profiling algorithm that assumes a monitor has
perfect gray balance. The robust/flexible/natural approach, is to
separate calibration from profiling, and make sure that the profiling
assumes nothing about the monitor response. If the calibration is good,
then the resulting profile with have relative PCS a*b* values of 0.0.
Graeme Gill.
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