[argyllcms] Re: dispwin vs xcalib loading LUT

Stefan Döhla wrote:
> 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

Hi Stefan, why 2.222 on Unix?
According to which standard/specification?

Regards,
Gerhard

> - 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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