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Accurate formula to measure display GAMMA !

by Rodney <PowerPCDeveloper@[EMAIL PROTECTED] > Jun 12, 2008 at 05:30 AM

Dear ALL,

I am in process of measuring GAMMA of my display device, and wanted
some advice for the same.  I refer
http://www.brucelindbloom.com/index.html?Eqn_BestGamma.html
to calculate the gamma value, but not getting the correct GAMMA value
as expected.

Steps, i used to measure GAMMA:

a) Measured Luminance  for various grayscale using  a calibrator.
GrayScale values (val, val, val)
where val range from 1 to 254

b) Normalized grayscale array by dividing each value by 255

c) Normalized luminance array by dividing each value by highest value
of luminance ( 197 in my case)

d) Used formula mentioned in
http://www.brucelindbloom.com/index.html?Eqn_BestGamma.html
to compute GAMMA

Also plotted graph on excel for those values. The graph is a proper
curve as expected. BUT, the gamma comes out to be 2.01 for a display
device which has a GAMMA of 2.2. I verfied the GAMMA of device by
measuring it with a third party application which gives GAMMA as 2.21.

Also i tested with other gamma values, my application could not give
correct GAMMA values.

What can be the issue ?
Is the formula accurate mentioned in this site ?
Can you please suggest some alternative formulae?

Please comment.

Thanks,
Rodney
 




 28 Posts in Topic:
Accurate formula to measure display GAMMA !
Rodney <PowerPCDevelop  2008-06-12 05:30:05 
Re: Accurate formula to measure display GAMMA !
Gernot Hoffmann <hoffm  2008-06-12 05:48:06 
Re: Accurate formula to measure display GAMMA !
Graeme Gill <invalid@[  2008-06-12 23:32:43 
Re: Accurate formula to measure display GAMMA !
Rodney <PowerPCDevelop  2008-06-12 17:19:45 
Re: Accurate formula to measure display GAMMA !
Gernot Hoffmann <hoffm  2008-06-13 00:23:33 
Re: Accurate formula to measure display GAMMA !
Rodney <PowerPCDevelop  2008-06-13 01:01:47 
Re: Accurate formula to measure display GAMMA !
Gernot Hoffmann <hoffm  2008-06-13 03:41:04 
Re: Accurate formula to measure display GAMMA !
Rodney <PowerPCDevelop  2008-06-15 18:20:56 
Re: Accurate formula to measure display GAMMA !
"Phil Sherrod"   2008-06-21 14:09:40 
Re: Accurate formula to measure display GAMMA !
Gernot Hoffmann <hoffm  2008-06-15 23:48:51 
Re: Accurate formula to measure display GAMMA !
Rodney <PowerPCDevelop  2008-06-16 03:41:39 
Re: Accurate formula to measure display GAMMA !
Gernot Hoffmann <hoffm  2008-06-16 07:41:03 
Re: Accurate formula to measure display GAMMA !
Gernot Hoffmann <hoffm  2008-06-19 10:33:22 
Re: Accurate formula to measure display GAMMA !
Rodney <PowerPCDevelop  2008-06-20 22:24:38 
Re: Accurate formula to measure display GAMMA !
Gernot Hoffmann <hoffm  2008-06-20 23:09:17 
Re: Accurate formula to measure display GAMMA !
Rodney <PowerPCDevelop  2008-06-21 01:13:12 
Re: Accurate formula to measure display GAMMA !
Gernot Hoffmann <hoffm  2008-06-21 02:53:52 
Re: Accurate formula to measure display GAMMA !
HA HUY THANH <thanhhah  2008-06-21 04:39:17 
Re: Accurate formula to measure display GAMMA !
Gerhard Fuernkranz <no  2008-06-21 21:20:00 
Re: Accurate formula to measure display GAMMA !
Gernot Hoffmann <hoffm  2008-06-21 08:03:49 
Re: Accurate formula to measure display GAMMA !
"Phil Sherrod"   2008-06-21 15:10:36 
Re: Accurate formula to measure display GAMMA !
HA HUY THANH <thanhhah  2008-06-21 11:48:29 
Re: Accurate formula to measure display GAMMA !
Gerhard Fuernkranz <no  2008-06-21 22:27:38 
Re: Accurate formula to measure display GAMMA !
HA HUY THANH <thanhhah  2008-06-21 20:26:02 
Re: Accurate formula to measure display GAMMA !
HA HUY THANH <thanhhah  2008-06-21 20:34:24 
Re: Accurate formula to measure display GAMMA !
Gerhard Fuernkranz <no  2008-06-22 11:29:47 
Re: Accurate formula to measure display GAMMA !
Gerhard Fuernkranz <no  2008-06-22 11:31:58 
Re: Accurate formula to measure display GAMMA !
Gernot Hoffmann <hoffm  2008-06-24 02:13:24 

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