POV-Ray : Newsgroups : povray.beta-test : [Doc] Photon TODO and Grey equation Server Time
29 Jul 2024 08:14:53 EDT (-0400)
  [Doc] Photon TODO and Grey equation (Message 1 to 4 of 4)  
From: Le Forgeron
Subject: [Doc] Photon TODO and Grey equation
Date: 30 May 2002 09:43:00
Message: <3CF62C99.5080905@free.fr>
Version 3.5.beta.RC5.icl.win32


In 6.10.5.1, range_divider (photons/advanced technique)

There is a "TODO" ... is there any hope for it ?






In 6.5.4.2 Functions in Isosurface,

the equation for the .gray seems bogus, it is given as
   gray value = Red*58.9% + Green*11.4% + Blue*29.7%

which means that Red is brighter than Blue which is brigher than Green.
IMHO, for the human eyes, it should be
   gray value = Red*29.7% + Green*58.9% + Blue*11.4%
(Because Green is brighter than Red which is brighter than Blue)
Unless Pov is made for some insects or bees ?


Post a reply to this message

From: Apache
Subject: Re: [Doc] Photon TODO and Grey equation
Date: 30 May 2002 10:21:43
Message: <3cf63577$1@news.povray.org>
I'm not an expert in this, but if green is already brighter shouldn't that
be compensated by a lower factor (like .114) instead of making it even more
bright in comparison to the other two colors?

--
Apache
POV-Ray Cloth experiments: http://geitenkaas.dns2go.com/experiments/
Email: apa### [at] yahoocom
ICQ: 146690431


Post a reply to this message

From: Le Forgeron
Subject: Re: [Doc] Photon TODO and Grey equation
Date: 30 May 2002 10:46:51
Message: <3CF63B59.1080001@free.fr>
Apache wrote:

> I'm not an expert in this, but if green is already brighter shouldn't that
> be compensated by a lower factor (like .114) instead of making it even more
> bright in comparison to the other two colors?

Not for getting the gray level.
When using gray, the order of colour is :

Black,  Blue,    Red,   Magenta, Green, Cyan,   Yellow and White.
<0,0,0>,<0,0,1>,<1,0,0>,<1,0,1>,<0,1,0>,<0,1,1>,<1,1,0> and <1,1,1>

Yellow is very light gray.
Green is middle grey
Red is dark grey
and Blue is very dark grey.

Try using the formula and then sort the values. Check the order!


Post a reply to this message

From: Nathan Kopp
Subject: Re: [Doc] Photon TODO and Grey equation
Date: 30 May 2002 18:01:18
Message: <3cf6a12e$1@news.povray.org>
"Le Forgeron" <jgr### [at] freefr> wrote...
> Version 3.5.beta.RC5.icl.win32
>
>
> In 6.10.5.1, range_divider (photons/advanced technique)
>
> There is a "TODO" ... is there any hope for it ?
>

The range_divider is no longer needed, so this section of the documentation
has been dropped.

-Nathan


Post a reply to this message

Copyright 2003-2023 Persistence of Vision Raytracer Pty. Ltd.