POV-Ray : Newsgroups : povray.binaries.tutorials : Gamma and Colour Values Server Time
31 Oct 2024 19:24:34 EDT (-0400)
  Gamma and Colour Values (Message 1 to 2 of 2)  
From: Dinesh Shah
Subject: Gamma and Colour Values
Date: 23 Feb 1998 13:45:39
Message: <34f1c525.0@news.povray.org>
Hi
I am attaching 4 jpgs which are created using various gamma values.

apart from that I have used various colour values from 0.5 to 4.0

Now my question is  greater value of colour increases the brightness of that
colour? And how gamma will help? Is gamma value is stored in the file?

--
Dinesh Shah :-)
din### [at] indiamailcom


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Attachments:
Download 'template10.jpg' (16 KB) Download 'template18.jpg' (15 KB) Download 'template20.jpg' (15 KB)

Preview of image 'template10.jpg'
template10.jpg

Preview of image 'template18.jpg'
template18.jpg

Preview of image 'template20.jpg'
template20.jpg


 

From: Tristan Wibberley
Subject: Re: Gamma and Colour Values
Date: 27 Feb 1970 09:51:21
Message: <01bd438e$1a1a7340$2a1657a8@W_tristan.gb.tandem.com>
Gamma is used to describe the peculiar properties of each individual
display device. 

On some monitors, a luminance value of 0 is displayed with lightness 0, and
a luminance value of 1 is displayed with lightness 1, but a luminance of
0.5 is displayed with lightness  ~0.2 because the actual appearance is not
linear (dark colours appear too dark). On other monitors, it is displayed
differently, the number that describes the deviation from linearity is
Gamma.

If you produce an image designed for viewing on a monitor with Gamma of
2.4, it will look wrong on a monitor with Gamma of 2.0. You can tell Povray
what the Gamma of the viewing method is (I can't remember the syntax
offhand), if the image is viewed on another monitor, the image must have
it's Gamma corrected for the new monitor. To do Gamma correction, you (or
whatever will do the correction) must know the original gamma of the image,
and the gamma of the display device. By storing the original Gamma with the
image you give half of that information, but I don't think JPEG provides
for that... PNG does, but that is no use unless the viewer corrects the
Gamma for their system.

For more information, search the web for "gamma".

Dinesh Shah <din### [at] indiamailcom> wrote in article
<34f1c525.0@news.povray.org>...
> 
> Hi
> I am attaching 4 jpgs which are created using various gamma values.
> 
> apart from that I have used various colour values from 0.5 to 4.0
> 
> Now my question is  greater value of colour increases the brightness of
that
> colour? And how gamma will help? Is gamma value is stored in the file?
> 
> --
> Dinesh Shah :-)
> din### [at] indiamailcom
> 
> 
> 
> 
> 
> 
> 
> 
>


Post a reply to this message

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