John Vodden wrote:

> I've tried following the instructions of how to use "gamma.gif" to determine
> the display gamma but I find that the gray on the left always looks
> significantly brighter than any of the numbered patches... does this mean
> that my moniter is much brighter than most or is it likely that I am doing
> something wrong? Are there any other ways of determining display gamma?



A natural gamma of more than 3 ?
Me think your system might already try to correct some gamma...and does 
it in the wrong direction.

Or you have turn the brightness too far ?

What is your system (hardware & OS please) ?

Check if your displaying program has not an option to automatically 
gamma correct a picture (you should desactivate it).

How I compute my gamma on W98, on a Voodoo3 2000 PCI:
=====================================================

I set the brightness of the monitor to "Centered",
Contrast was 100%, and the gamma control center was set to a gamma of 1.0!
I opened gamma.gif with xnview (and in the options tab, the gamma
correction was not active)
instead of going 5 meters away, I closed my eyes and reopened just 
enoough to get a blurry feeling, comparing the left part with the right 
part, I found a change in the feel of the grey between 2.6 and 2.8, so I
popped up the gamma control of the card, tuned the gamma knob to 2.7 and 
look again at the picture: the change of grey was now for the 1.0 entry.
So, I know that my system gamma is 2.7 when there is no gamma correction.

What I'm not sure yet, is wether I should kept a correction of 2.7 or 
one of 1.0 or just another one which would give a system gamma between 
1.0 and 2.7

Given that most viewer (including browser) do not gamma correct PNG 
files, and that I want to see the portfolio t_Grnt15 & t_Grnt17 images
(which are very black with a gamma of 2.7), I believe I will keep the 
correction of 2.7 so that my system just behave like a 1.0 display.
It might means more details in the shadows.

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