Yo,

"clipka" <nomail@nomail> wrote in message 
news:web.4986021ec6af8354f8450bd80@news.povray.org...
> Ever wondered how on earth you could verify that your POV gamma settings 
> are ok?
> This scene is the answer.

    Perhaps I'll end up looking foolish .... Oh well!! here goes.

    ..... this is rather like the example that's in docs .... right?

> When viewed with squinted eyes (or without glasses, if you need them for
> computer work), the shot should seem to show nothing but a plain gray
> rectangle. If that is the case, your gamma settings are ok. Use these
> (including the "assumed_gamma" setting) for *ALL* scenes you do. If that 
> makes
> your other scenes look too bright or too dark, it's *NOT* the gamma's 
> fault,
> but the lighting conditions'. Note that wrong gamma settings will mess up 
> color
> saturation in your scenes in a nonlinear, unrealistic way.

    I wasn't able to get the results that you seem to be eluding to .... the 
idea is to have the sphere appear to meld into the background correct?

> Make sure you do *NOT* tamper with the "assumed_gamma 1.0" statement if 
> you can
> help it. If you absolutely must to get proper results with both preview 
> and
> file output, make sure you use the same value in your other scenes as 
> well.
>
> With POV 3.6, the setting you will want to toy around with is 
> "Display_Gamma".
> With POV 3.7, you also have the possibility of toying around with 
> "File_Gamma"
> separately to change your output files' gamma. This may be especially 
> handy if
> your display gamma is something other than 2.2, but you want to create 
> files
> ready for the internet, where a display gamma of 2.2 is a quasi-standard.

    I'm running v3.6 and using the example in docs I've arrived at 
Display_Gamma = 2.5 for my display and using that value forever. I 
understand how this works just by simple empirical testing .... lower value 
for D_G makes image darker .... higher lighter. It used to be that some 
folks have crt some lcd .... now a days it's pretty much lcd .... does that 
make a diff? I'm using the color profile that came with the display, my vid 
card (nvidia) has an applet that allows to adjust gamma curve, I've left 
that alone (default says gamma=1.0).

You know with all the variables it's no wonder that (gamma correction) is a 
frustrating excerise to say the least.

Jim

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