Hello,

After using 3.6 since release I have just started to play with POV-Ray 
3.7 beta35a in Windows XP SP3. After testing and reading the release 
notes I found some behavior that maybe I just do not understand.

Does the display_gamma setting modify the output image at all? The 
rendered image in POV-Ray looks fine but if I view it in another 
program, such as Gimp, IrfanView or Paint.net, its either too bright or 
too dark. No matter what value I put for display_gamma the image is 
always the same although it changes in the POV-Ray render window. I 
tried all the export formats with the same results. I kept file_gamma as 
1.0 and did not use assumed_gamma.

So with POV-Ray 3.7 do I have to gamma correct all the renders 
separately in another program? I understand that baking the gamma into 
the image may be bad in terms of portability but if the setting is not 
read by some viewers it may be nice if it could optionally be baked in.

thanks,

FlyerX

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FlyerX <fly### [at] yahoocom> wrote:
> Does the display_gamma setting modify the output image at all?

  display_gamma affects the preview window. Its purpose is to be the
proper gamma for your system (that's usually 2.2).

> I kept file_gamma as 1.0 and did not use assumed_gamma.

  file_gamma should usually be the same as display_gamma, because that way
you are telling which display_gamma you were using when you made the image.

  (I have to admit that I don't remember now why display_gamma and file_gamma
are two separate values instead of being just one and the same.)

> So with POV-Ray 3.7 do I have to gamma correct all the renders 
> separately in another program?

  No, you specify the proper file_gamma.

-- 
                                                          - Warp

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On 1/18/2010 6:17 PM, Warp wrote:
> FlyerX<fly### [at] yahoocom>  wrote:
>> Does the display_gamma setting modify the output image at all?
>
>    display_gamma affects the preview window. Its purpose is to be the
> proper gamma for your system (that's usually 2.2).
>
>> I kept file_gamma as 1.0 and did not use assumed_gamma.
>
>    file_gamma should usually be the same as display_gamma, because that way
> you are telling which display_gamma you were using when you made the image.
>
>    (I have to admit that I don't remember now why display_gamma and file_gamma
> are two separate values instead of being just one and the same.)
>
>> So with POV-Ray 3.7 do I have to gamma correct all the renders
>> separately in another program?
>
>    No, you specify the proper file_gamma.
>

Making file_gamma the required value worked.

Thanks,

FlyerX

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Warp <war### [at] tagpovrayorg> wrote:
> FlyerX <fly### [at] yahoocom> wrote:
> > Does the display_gamma setting modify the output image at all?
>
>   display_gamma affects the preview window. Its purpose is to be the
> proper gamma for your system (that's usually 2.2)...
.....(etc.)...

A very clear, simple and concise explanation. Thanks, Warp.  IMO, this should be
made part of the 'new' documentation, practically as-is.

Ken

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Kenneth <kdw### [at] earthlinknet> wrote:
> A very clear, simple and concise explanation. Thanks, Warp.  IMO, this should be
> made part of the 'new' documentation, practically as-is.

  There's already a thread about the subject.

-- 
                                                          - Warp

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