[argyllcms] Re: dispwin vs xcalib loading LUT
- From: Stefan Döhla <color@xxxxxxxxx>
- To: Frédéric <argyllcms@xxxxxxxxxxxxx>
- Date: Mon, 1 Jan 2007 13:22:11 +0100
Hi Frederic, Graeme,
>> Not being the author of xcalib, not without some effort. Can you clarify
>> a little how xcalib and dispwin behave on these two profiles (ie.
>> description of four cases).
I am, however I'm not the author of dispwin ;-)
When I started xcalib, I crosschecked with some other calibration
loaders to find out why gamma 1.0 in the vcgt tag makes the screen
darker when using these other loaders - 1.0 was supposed to mean
linear ...
Therefore I took the system gamma into account, which is 2.2 on Win32
and 2.222 on Unixes - voila: results were the same!
The ramp is then created from the gamma values rGamma, rMax and rMin like this:
for(j=0; j<nEntries;j++)
{
ramp[j] = 65536.0 *
pow (j * (rMax - rMin) / nEntries, rGamma * SYSTEM_GAMMA)
+ rMin);
}
I think xcalib's behaviour is correct - at least if the
result is compared to other calibration loaders like the WindowsXP
color panel, ...
Happy new year everyone
Stefan
--
mailto:color@xxxxxxxxx
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