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No binaries, just a diff for official 3.5.
http://news.povray.org/povray.binaries.images/28651/
http://luxlab.com/files/exposure.diff.gz
_____________
Kari Kivisalo
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Added a new keyword and documentation. The previous link is redirected.
http://luxlab.com/files/exposure.htm
_____________
Kari Kivisalo
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Kari Kivisalo wrote:
> Added a new keyword and documentation. The previous link is redirected.
> http://luxlab.com/files/exposure.htm
>
>
> _____________
> Kari Kivisalo
Hi Kari,
When you say
'color = exposure_gain*(1 - exp(-exposure*color))'
I guess you are applying it to each of the colour channels separately?
Could you add an option to apply it to the 'luminosity' of the pixel
instead? This would keep the 'hue' and 'saturation' of the colour
unchanged, just compress the brightness ...
Just a thought,
Mike Andrews.
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In article <3dd0fe06@news.povray.org>,
Michael Andrews <m.c### [at] reading acuk> wrote:
> I guess you are applying it to each of the colour channels separately?
> Could you add an option to apply it to the 'luminosity' of the pixel
> instead? This would keep the 'hue' and 'saturation' of the colour
> unchanged, just compress the brightness ...
Nice idea, but I don't think that's how either film or the eye works.
They both have red-green-blue sensitive portions that are probably
affected equally (or nearly so) by the processes that cause this.
--
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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Michael Andrews wrote:
>
> I guess you are applying it to each of the colour channels separately?
This is how color films work. The emulsions for primary colors
react independently.
> Could you add an option to apply it to the 'luminosity' of the pixel
> instead?
It could be applied to the CIE luminance component but would it
be usefull? I'll add it anyway because I'm curious :)
_____________
Kari Kivisalo
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Christopher James Huff wrote:
> Nice idea, but I don't think that's how either film or the eye works.
> They both have red-green-blue sensitive portions that are probably
> affected equally (or nearly so) by the processes that cause this.
>
I'm sure it's not how film works. :-)
On the other hand I seem to remember reading that because of the
interconnections locally in the retina the brain tends to process
something like hue-saturation-intensity rather than RGB ... whether this
has any bearing on the matter I'm not sure.
Bye for now,
Mike Andrews.
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Kari Kivisalo wrote:
> It could be applied to the CIE luminance component but would it
> be usefull? I'll add it anyway because I'm curious :)
Is there ever a better reason ? :-)
I look forward to seeing if it makes any visual difference.
Bye for now,
Mike Andrews.
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Michael Andrews wrote:
>
> On the other hand I seem to remember reading that because of the
> interconnections locally in the retina the brain tends to process
> something like hue-saturation-intensity rather than RGB
I'm not trying to model human visual system here. That would require
way more processing and would have to operate on the whole image.
I tested the luminance processing in Photoshop and the results didn't
look that good so at the moment I'll just stick to what I know works.
I may include it later.
_____________
Kari Kivisalo
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In article <3dd24eef$1@news.povray.org>,
Michael Andrews <m.c### [at] readingacuk> wrote:
> On the other hand I seem to remember reading that because of the
> interconnections locally in the retina the brain tends to process
> something like hue-saturation-intensity rather than RGB ... whether this
> has any bearing on the matter I'm not sure.
That may be so, but the pupil and individual rods and cones are the main
causes of brightness adaptation and other nonlinear response. If you can
produce a response using a smaller brightness range that the brain would
get from a brighter light source, the image will look brighter. Part of
why the sun in sunset images seems brighter than a white sheet of paper.
--
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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