In article <cja### [at] netplexaussieorg>,
 Christopher James Huff <cja### [at] earthlinknet> wrote:
> You have a lot of lights, and they are all using full-brightness colors. 
> Colors are composed of 3 float values, one for each of red, green, and 
> blue. Although internally their range is practically unlimited, they are 
> clipped to the range [0, 1] for output. A value of 1 is full brightness, 
> and going higher will not have any effect. If you have 100 green lights 
> and 2 red lights, it won't matter how much more brightly lit in green 
> the surface is. A point lit with < 2, 100, 0> will appear to be < 1, 1, 
> 0> yellow. Basically, you just need to drastically reduce the brightness 
> of your lights, and probably should use distance fading as well. And you 
> should seriously look at whether all those lights are necessary...it 
> looks like you may be trying to make area lights.


I thought that I read somewhere that a light defined as color rgb 2 
would be white, but twice as bright as normal.  Is this true?  Did 
anyone else read this? Am I insane?  I didnt think this was possible, as 
the light could only get so bright, but please put my doubts to rest.

Thanks

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In article <mat### [at] netplexaussieorg>,
 Matthew Pace <mat### [at] lycoscom> wrote:

> I thought that I read somewhere that a light defined as color rgb 2 
> would be white, but twice as bright as normal.  Is this true?  Did 
> anyone else read this? Am I insane?  I didnt think this was possible, as 
> the light could only get so bright, but please put my doubts to rest.

Well, I pretty much just said so, though not using that specific 
example. It is white and twice as bright as rgb < 1, 1, 1>. Your monitor 
can only display colors with a limitedd range of brightness and most 
file formats only store percentages of maximum brightness rather than 
absolute brightness, so the colors are clipped at output. There is no 
difference in the final output between a color that the camera saw as < 
2, 7, 1> and one that was only < 1, 1, 1>.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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de news: cja### [at] netplexaussieorg...
Your monitor
> can only display colors with a limitedd range of brightness and most
> file formats only store percentages of maximum brightness rather than
> absolute brightness, so the colors are clipped at output.
But pixels colors are computed from light color>fade due to distance>object
pigment/diffuse properties... so not inevitably clipped.
If you want maximum dynamic range in your image (i.e white highlights and
black most dark shadows) you can multiply your light color.

Marc

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In article <3faf4d7a$1@news.povray.org>,
 "Marc Jacquier" <jac### [at] wanadoofr> wrote:

> Your monitor
> > can only display colors with a limitedd range of brightness and most
> > file formats only store percentages of maximum brightness rather than
> > absolute brightness, so the colors are clipped at output.
> But pixels colors are computed from light color>fade due to distance>object
> pigment/diffuse properties... so not inevitably clipped.

Distance fading is off by default and scenes usually have at least some 
pigment/diffuse properties that come close to white.


> If you want maximum dynamic range in your image (i.e white highlights and
> black most dark shadows) you can multiply your light color.

By what?
Yes, you can pack more information into the output image by making sure 
the lighting is dark enough that clipping is minimized, and then 
post-processing the scene to get the normally lit portions (which are 
now very dark because of the light scaling) to show up right. However, 
this has bad precision effects...a 24-bit image has 8 bits per color 
component. That's 256 levels from black to 100% intensity. If you use 
100% to mean 2x max viewable intensity, you've just limited the normal 
[0, 1] range of lighting to 128 levels of intensity. If 100% means 10x 
max viewable intensity, you limit it to 25 levels.

You could render multiple images at different color scales and combine 
their data, but your best bet is to just use a patch that adds a high 
dynamic range output format.

-- 
Christopher James Huff <cja### [at] earthlinknet>
http://home.earthlink.net/~cjameshuff/
POV-Ray TAG: chr### [at] tagpovrayorg
http://tag.povray.org/

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