[Digikam-users] Gamma on Linux

[Leonardo Giordani]

Thank you, now the whole thing is clear :)

2010/2/3 Milan Knížek <knizek.confy at volny.cz>:
> Leonardo Giordani píše v St 03. 02. 2010 v 16:22 +0100:
>> Hi all,
>>
>> I'm trying to understand the gamma tuning of Linux: I always read on
>> Internet that we aim at gamma 2.2, but if I set Gamma 2.2 through
>> xgamma, I get a way too bright monitor, I cannot even see black. The
>> best value (without real calibration) is 1.0 (xgamma -gamma 1.0).
>
> Your monitor has definitely native gamma around 2.4 - 2.5. Higher native
> gamma results in darker mid-tones.
>
> xgamma (or setting in /etc/X11/xorg.conf or the video driver tools like
> nvidia-settings panel) tells X server to change the gamma of video card
> LUT (look-up-table). Adjustments bigger then 1 make the mid-tones
> lighter.
>
> Additionally, there are tools (xcalib, dispwin) which can do finer
> adjustments to the video card LUT then just the simple xgamma. However,
> one needs to use a calibration device.
>
> What you finally see on your screen is a result of monitor's native
> gamma and any gamma adjustments to video card LUT. (Monitor gamma
> divided by LUT gamma.)
>
>> I'm a bit puzzled by this: what is the nominal gamma of my monitor (a
>> Samsung SyncMaster, so a very common one)? If it is 2.2 why shall I
>> set it to 1.0?
>
> The various tools for gamma adjustments do not tell you what is the
> visual gamma, but only what gamma adjustment is done to LUT.
>
> regards,
>
> Milan Knizek
> knizek (dot) confy (at) volny (dot) cz
> http://www.milan-knizek.net - About linux and photography (Czech
> language only)
>
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