POV-Ray : Newsgroups : povray.advanced-users : lightsys and gamma Server Time
1 Jun 2024 04:20:10 EDT (-0400)
  lightsys and gamma (Message 1 to 5 of 5)  
From: posfan12
Subject: lightsys and gamma
Date: 19 Jun 2011 13:30:01
Message: <web.4dfe312b56bb9cc3b67b29550@news.povray.org>
Is there anything special I need to do to update scenes created with lightsys in
POV 3.6 to the new gamma system? Or, can I leave the settings alone?

Thanks!


Mike


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From: Jaime Vives Piqueres
Subject: Re: lightsys and gamma
Date: 20 Jun 2011 02:56:56
Message: <4dfeef38$1@news.povray.org>

> Is there anything special I need to do to update scenes created with
> lightsys in POV 3.6 to the new gamma system? Or, can I leave the
> settings alone?
>

   AFAIK, no... in fact, it was designed to be used with
assumed_gamma=1.0. In general, the only change needed for 3.7 is to
adapt the default skydome finish to use "emission" instead "ambient",
but that can be already done by declaring "fiLuminous" before calling
the include.

   Regards,

-- 
Jaime Vives Piqueres
		
La Persistencia de la Ignorancia
http://www.ignorancia.org


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From: Ive
Subject: Re: lightsys and gamma
Date: 20 Jun 2011 03:06:54
Message: <4dfef18e$1@news.povray.org>
Am 19.06.2011 19:26, schrieb posfan12:
> Is there anything special I need to do to update scenes created with lightsys in
> POV 3.6 to the new gamma system? Or, can I leave the settings alone?

As lightsysIV did already require to have an assumed_gamma 1.0 statement 
within the global settings there has nothing changed.
Just make sure to use the latest version of lightsys that should work 
well with 3.7 as it has some unnecessary #version statement (my fault!) 
removed.

-Ive


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From: posfan12
Subject: Re: lightsys and gamma
Date: 21 Jun 2011 12:10:01
Message: <web.4e00c232b1c18060b4e9c8df0@news.povray.org>
Jaime Vives Piqueres <jai### [at] ignoranciaorg> wrote:
>    AFAIK, no... in fact, it was designed to be used with
> assumed_gamma=1.0. In general, the only change needed for 3.7 is to
> adapt the default skydome finish to use "emission" instead "ambient",
> but that can be already done by declaring "fiLuminous" before calling
> the include.
>
>    Regards,
>
> --
> Jaime Vives Piqueres
>
> La Persistencia de la Ignorancia
> http://www.ignorancia.org

Yes, but on Windows at least the default output in 3.7 is closer to
assumed_gamma=2.2, thus some modification is needed, yes?


Mike


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From: Alain
Subject: Re: lightsys and gamma
Date: 21 Jun 2011 22:13:39
Message: <4e014fd3@news.povray.org>

> Jaime Vives Piqueres<jai### [at] ignoranciaorg>  wrote:
>>     AFAIK, no... in fact, it was designed to be used with
>> assumed_gamma=1.0. In general, the only change needed for 3.7 is to
>> adapt the default skydome finish to use "emission" instead "ambient",
>> but that can be already done by declaring "fiLuminous" before calling
>> the include.
>>
>>     Regards,
>>
>> --
>> Jaime Vives Piqueres
>>
>> La Persistencia de la Ignorancia
>> http://www.ignorancia.org
>
> Yes, but on Windows at least the default output in 3.7 is closer to
> assumed_gamma=2.2, thus some modification is needed, yes?
>
>
> Mike
>
>

For the display, it's "display_gamma" from the main ini file. It only 
affect how the image is displayed in the preview.
For the output file, at least with PNG, it's "file_gamma". For a PNG 
file, it set the gamma chunk of the file. For other formats that don't 
support that, it adjust the data in the file.
display_gamma and file_gamma sould normaly have the same value.

It seems that, if they are not explicitely set, they default to 2.2.

BUT, as the computation is performed, it should be assumed_gamma 1 to 
use a linear colour space.


Alain


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