Am 03.01.2011 07:36, schrieb Dave Blandston:

> I'm sure I am doing something wrong. In order to get everything looking good on
> my monitor (CRT), I set the video card gamma to +1.0. If I set it lower or
> higher I CANNOT get things to look right by adjusting the brightness and
> contrast settings. If I set my video card to gamma 2.2 it looks absolutely
> terrible.

There may be a potential for misunderstanding there: Your overall 
display gamma is the result of multiple component gammas - including the 
monitor, graphics card hardware, graphics card drivers, and even 
possibly some OS settings. The video card driver may - or may not - tell 
you only the "LUT gamma" (i.e. the graphics card driver's part of the 
whole thing). In that case a value of 1.0 is a pretty good setting, but 
is /not/ what you need to set POV-Ray's Display_Gamma to.

Did you ever check the gamma with the test images in the documentation, 
or some site on the internet? The 3.7.0.RC1 also comes with a section on 
gamma handling, and a sample scene to check whether your settings are 
"sane".

> You are right, I'm using POVRAY.INI settings "file_gamma=1.0" and
> "display_gamma=1.0." I added "assumed_gamma 1.0" to the scene file. Everything
> looks great on my computer (render preview and finished images displayed with
> any program other than Internet Exporer) but .png images look washed out when
> displayed in Internet Explorer. Between the video card settings, POVRAY.INI
> settings, assumed_gamma setting, and monitor brightness settings something must
> be wrong. (I don't think Windows XP has any gamma settings other than what the
> video card driver adds.) But after lots of experimentation, the only thing that
> doesn't work for me is the display of .png files with Internet Explorer so if I
> convert to .jpg before posting everything will be fine.
>
> By the way, even when I turn the file_gamma way down the image still appears
> washed out in IE. I suspect there's something wrong with the way IE version 7
> handles gamma. (At least it's different from all the other display programs I
> use.)

No, IE is probably the only piece of software you have that's doing it 
right.

 From all you tell me, I assume that your overall display gamma is 
indeed around 2.2, and that you're currently "cheating" your way around 
what assumed_gamma 1.0 is intended to do. Note that the combination 
Display_Gamma=File_Gamma=assumed_gamma=1.0 is virtually equivalent to 
Display_Gamma=File_Gamma=assumed_gamma=2.2 /except for PNG output/.

So here's what you should do:

(1) Check your display gamma, using one of the many gamma test patterns 
out there, such as the image in section 3.1.2.3.2 "Setting your Display 
Gamma" of the POV-Ray 3.6 docs, or using the sample scene mentioned in 
the tutorial section "Gamma Handling" of the 3.7.0.RC1 docs. I suspect 
you'll learn that your display gamma /is/ around 2.2.

(2) Set Display_Gamma=2.2 and File_Gamma=2.2

(2.1) Note that this will /always/ give you that washed-out appearence 
you're currently seeing with .png in IE.

(3) To compensate, either (a) go back to using assumed_gamma 2.2 (*), or 
(b) learn how to texture and illuminate your scene for physically 
accurate rendering, and/or (c) get used to the more washed-out look and 
learn to like it.

(* As of 3.7.0.RC1, assumed_gamma is no longer considered deprecated; to 
the contrary, it will be /mandatory/ in the future; and while the 
recommendation to use a value of 1.0 is still maintained for /physically 
accurate/ renders, it is now acknowledged that people may prefer other 
properties over physical accuracy. The new gamma handling features have 
also been adapted to play nice with assumed_gamma.)

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