Photoshop v 4.01 (Win)

"Monitor Gamma" and Gamma Slider value pairs that make Photoshop calibration linear (disables the Photoshop monitor calibration).

Monitor    Gamma
Gamma     Slider
--------     -------
1,0       none, apparently a bug.
1,1      -100
1,2      -91
1,3      -82
1,4      -73
1,5      -64
1,6      -55
1,7      -46
1,8      -36
1,9      -27
2,0      -18
2,1       -9
2,2       +0
2,4       +9
2,6      +18
2,8      +27
3,0      +36

Calculate the actual Gamma correction of Photoshop

Mr. M.C. Adler from Chromatic cleverly figured out the the mathematical function that the "Monitor Gamma" and Gamma Slider follows:

For gamma slider values <= 0:

Adjusted Gamma = (2.2/Monitor Gamma)*(1 + Gamma Slider/200)

For gamma slider values >= 0:

Adjusted Gamma = (2.2/Monitor Gamma)*(1 + Gamma Slider/100)

Where: Adjusted Gamma = the gamma compensation from the image to the
display.

The function gives exactly that amount of gamma compensation that is buried into the RGB byte values of the image file, after the image is manipulated. It is not the exact amount of the "Monitor Gamma" value itself because there is error in the Gamma Strip in the Calibrate dialog. The error depends on the quality of the monitor and display driver card and can be several tithes.

Frequently needed Gamma Spaces for Photoshop

When working with linearly calibrated system the following "Monitor Gamma" and Gamma Slider value pairs are usually needed frequently for quick checking:

Gamma Space	"Monitor Gamma"	Gamma Slider
Linear	1.1	-100
2.5	1.1	25
2.2	1.1	10
1.8	1.1	-20

Accurate gamma space if you know the gamma of your monitor

The Below Gamma Slider values will set the Photoshop calibration so that the "Monitor Gamma" value in the MonitorSetup dialog will be the accurate gamma space of Photoshop. In order to use the below values the actual physical gamma of the monitor must be known (or it can be usually determined by the platform).

If your monitor has this gamma	Then set the Gamma Slider to:
2,8	27
2,7	23
2,6	18
2,5 (PC system default gamma)	14
2,4	9
2,3	5
2,2	0
2,1	-9
2	-18
1,9	-27
1,8 (Mac system default gamma)	-36
1,7	-45
1,6	-55
1,5	-64
1,4	-73
1,3	-82
1,2	-91
1,1	-100

Accurate Image Manipulation for Desktop Publishing