Am 01.03.2012 04:13, schrieb JamesB7271:
> Hello,
>
> I am new to POV-Ray and have just upgraded from POV-Ray 6 to POV-Ray 7. I notice
> now that all my renders seem too bright. As an extreme example: if I render a
> simple sphere over a flat plane in a scene that has no light sources, I can
> clearly see both the sphere and the plane (although somewhat dimmed). With
> version 6 I believe a scene with no light sources would render completely black,
> which I think is correct for a scene with no lights.<-(is this a correct
> assumption?)
>
> I read that there were some changes made to Gamma settings in version 7? How do
> I get it back to normal?

(Just for the records: I tend to become somewhat itchy when people refer 
to the 3.6 or even 3.5 gamma handling as "normal", because it isn't - 
it's obsolete, with POV-Ray 3.7's default gamma handling being far 
superior.)

There are multiple ways of achieving what you're asking for, the 
simplest being to tell POV-Ray that your scene was designed for POV-Ray 
3.6; just insert the following line at the beginning of your scene file:

     #version 3.6;

POV-Ray 3.7 will then (among other things) automatically switch to a 
gamma handling mode that is backward compatible with POV-Ray 3.6 (with 
minor exceptions relating to PNG input images).

In addition, if you explicitly specify "Display_Gamma" somwehere in your 
.ini files, you also need to set "File_Gamma" to the same value (unless 
you're using PNG, OpenEXR or Radiance HDR as output format).

If you do not specify "Display_Gamma", you may still see slight 
differences in dark image regions; if you consider that a problem, 
explicitly specify "Display_Gamma=2.2" and "File_Gamma=2.2" to iron 
those out.


Alternatively, specifying "assumed_gamma srgb" will give you essentially 
the same gamma-related behaviour as POV-Ray 3.5 (or POV-Ray 3.6 without 
any "assumed_gamma" statement), except for gamma handling of any input 
images.

If your scenes already contain an "assumed_gamma" statement, gamma 
handling in 3.7 /should/ automatically be essentially the same (again 
except for input images), and your observed changes should be a no-issue.

In both cases, the aforementioned advice for "Display_Gamma" and 
"File_Gamma" also applies.


I hope this helps. For future scenes, if realism is of any concern to 
you I strongly recommend using "#version 3.7" and "assumed_gamma 1.0", 
leaving "File_Gamma" at its default, and using the new "srgb" family of 
color keywords instead of "rgb" to specify colors taken from external 
applications.

Post a reply to this message