POV-Ray : Newsgroups : povray.newusers : conversion Server Time
17 Aug 2022 21:34:26 EDT (-0400)
  conversion (Message 1 to 3 of 3)  
From: David Kraics
Subject: conversion
Date: 3 Aug 2022 12:55:00
Message: <web.62eaa74abd9127441c1b6180a57e0@news.povray.org>
How do I convert from the 255 scale rgb numbers to decimal numbers used by
POV-Ray? Apparently dividing the number by 255 doesn't work.


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From: Alain Martel
Subject: Re: conversion
Date: 4 Aug 2022 07:15:21
Message: <62ebaa49$1@news.povray.org>
Le 2022-08-03 à 12:50, David Kraics a écrit :
> How do I convert from the 255 scale rgb numbers to decimal numbers used by
> POV-Ray? Apparently dividing the number by 255 doesn't work.
> 

Normally, 0..255 scale rgb values are in the sRGB space.
To use them, you need to do this :
1) In the global_settings block, set assumed_gamma 1
2) In your pigment, use srgb instead of just rgb.

When you use rgb, POV-Ray use linear range.
When you use srgb, POV-Ray use the sRGB tranfert formula to convert the 
non-linear ranges of the sRGB colour space into the linear range of the 
rgb colour space.

The format is :

pigment{ srgb sRGB_Colour/255 }


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From: kurtz le pirate
Subject: Re: conversion
Date: 5 Aug 2022 13:19:32
Message: <62ed5124$1@news.povray.org>
On 03/08/2022 18:50, David Kraics wrote:
> How do I convert from the 255 scale rgb numbers to decimal numbers used by
> POV-Ray? Apparently dividing the number by 255 doesn't work.
> 

What do you mean by "number" ?


Alain answered precisely and we can add that :
if c = red 0..255 green 0..255 blue 0..255, then the division of c/255
will give well the color with the values between 0.0 and 1.0.

And "pigment { color c }" will be interpreted correctly by POVRay



-- 
Kurtz le pirate
Compagnie de la Banquise


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