Information re. display gamma

[Milan Knížek]

Getting back to update of the text: 
> --
> Gamma is adjusted to affect the color of the attached monitor.
> Traditionally Linux has used a gamma value of 1.0, but this makes
> monitors look washed out compared Windows XP or OS X. Apple
> traditionally used a value of 1.8 for a long time, but now use the same
> value as Microsoft. Microsoft has always used a value of 2.2.
> --

Taking into account Graeme's points (thanks, it was helpful), how about
this:

(The GCM gamma fine tuning tool remains as it is - i.e. pure adjustment
to LUT, not taking care about the monitor native gamma)

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Overall system gamma is a product of image encoding gamma, video card
gamma and native gamma of the monitor and normally it should be equal to
1. You may want to adjust gamma to allow for non-standard viewing
conditions (e.g increasing gamma in dim light at home). Refer to User
Manual for more details.
---
And this be included in User Manual:
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CRT monitors have native gamma around 2.4 - 2.5 and LCD monitors usually
emulate the same value.

Traditionally, Linux and MS Windows operating systems use image encoding
of 1/2.2 and do not apply any gamma adjustment to the image or video
card LUT. Therefore the overall gamma is expected to be around 1.1
(which is useful to allow for dim viewing conditions at home
environment).

Apple used to use image encoding gamma close to 1/1.8 to naturally match
the native gamma of printing devices (and therefore internally applied
gamma adjustment of 1/1.45 before displaying images on monitor so that
the images displayed correctly).

Nonetheless, since OS X (v10.6 Snow Leopard) the default image encoding
gamma has also the value of 1/2.2 to meet the requirements of consumer
imaging industry.

Before fine tuning the gamma in GCM, you should know what your monitor
native gamma is, what display gamma you want to reach and then do the
math yourself.
---

regards,

Milan Knizek
knizek (dot) confy (at) volny (dot) cz
http://www.milan-knizek.net - About linux and photography (Czech
language only)