I'm often finding that when I bring up the color histogram for a completed
work,  I haven't used the full color range-- things are kind of washed out
to medium levels of brightness.

Any tips on how to maximize contrast in the artistic color sense (don't mean
compositional sense)?

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Greg M. Johnson wrote:
> Any tips on how to maximize contrast in the artistic
> color sense (don't mean compositional sense)?

For a single image you can just do it in an image-manipulation program I
guess?

For an animation, you could place a tiny sphere around your camera with a
contrast filter texture.

Rune
-- 
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com
POV-Ray Ring: http://webring.povray.co.uk

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"Rune" <run### [at] runevisioncom> wrote in message news:415ead8d$1@news.povray.org...
[deletions]
: For an animation, you could place a tiny sphere around your camera with a
: contrast filter texture.

Explain please?
=Bob=

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> : For an animation, you could place a tiny sphere around your camera with a
> : contrast filter texture.

> Explain please?

I think he's refering to a sample scene shipped with POV:
<Your POV Directory>/scenes/textures/pigments/transmitfx.pov

Author: Rune. Should have guessed that :)

HTH,
Florian
-- 
camera{look_at-y*10location<8,-3,-8>*10}#local a=0;#while(a<999)sphere{
#local _=.01*a-4.99;#local p=a*.01-5;#local c=.01*a-4.995;<sin(p*pi)*5p
*10pow(p,5)*.01>sin(c*c*c*.1)+1pigment{rgb 3}}#local a=a+1;#end
/******** http://www.torfbold.com ******** http://www.imp.org ********/

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"Florian Brucker" <tor### [at] torfboldcom> wrote in message
news:415f059b@news.povray.org...
: > : For an animation, you could place a tiny sphere around your camera with a
: > : contrast filter texture.
: > Explain please?
:
: I think he's refering to a sample scene shipped with POV:
: <Your POV Directory>/scenes/textures/pigments/transmitfx.pov
:
: Author: Rune. Should have guessed that :)

Thanks! I will check it out.
=Bob=

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415e9f60$1@news.povray.org...
> I'm often finding that when I bring up the color histogram for a completed
> work,  I haven't used the full color range-- things are kind of washed out
> to medium levels of brightness.
>
> Any tips on how to maximize contrast in the artistic color sense (don't 
> mean
> compositional sense)?

It's not easy. I think that the best way is to mimic real life lighting as 
much as possible.

- Get rid of the default ambient 0.1 in the finish.
- Use high intensity values for lights. See Jaime's lightsys macro for 
instance. In any case, the trick, for indoor lights, is to have very high 
intensities and very short fade distances.
- Use darker pigment and colours than one would think (sampling colours from 
photographs is often very telling)
- Rely on radiosity for indirect lighting. The 3.6 unclipped values can give 
beautiful results. Keep the recursion level as low as possible (1 tend to 
give the best constrast, 2 and 3 give more subtle results).

When doing such complex adjustments, it may be practical to use variables to 
control the brightness of lights and the diffuse values of textures. For 
instance you can have the finish statement written like {ambient 0 diffusion 
0.7*Global_Diffusion} and then use the Global_Diffusion value to control the 
way textures look throughout the scene.

It still may be necessary to manipulate the colours in Photoshop (or 
equivalent), for instance by playing with the tone levels. Beware of not 
losing too many colours though.

G.


-- 
**********************
http://www.oyonale.com
**********************
- Graphic experiments
- POV-Ray and Poser computer images
- Posters

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Gilles Tran wrote:
> - Use darker pigment and colours than one would think (sampling colours from 
> photographs is often very telling)

You need to make sure to remove gamma correction before doing that, 
otherwise you will always get too bright colors.

> like {ambient 0 diffusion 0.7*Global_Diffusion}

a diffusion of syntax from an alternate reality? ;-)

Christoph

-- 
POV-Ray tutorials, include files, Sim-POV,
HCR-Edit and more: http://www.tu-bs.de/~y0013390/
Last updated 23 Sep. 2004 _____./\/^>_*_<^\/\.______

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In Rune's file,  it looks like medium-bright areas get brighter, whereas,
medium-dark areas get DARKER.

WTheck?

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Greg M. Johnson wrote:
> In Rune's file,  it looks like medium-bright areas
> get brighter, whereas, medium-dark areas get DARKER.

Yep, that's usually the point of contrast, isn't it? :)

Here's the logic behind the trick:

As we all know, if you use a transmit value between 0.0 and 1.0, then colors
seen through this pigment will get nearer to your specified rgb color.

If you use rgb 1.0 transmit 0.5 then all colors will get nearer to rgb 1.0.
If you use rgb 0.0 transmit 0.5 then all colors will get nearer to rgb 0.0.
If you use rgb 0.5 transmit 0.5 then all colors will get nearer to rgb 0.5.

The closer the transmit value is to 1.0, the less the colors seen through
the pigment will get near your specified rgb color. When transmit is 1.0,
then the colors seen through the pigment will not get near your specified
rgb color at all, but just stay the same.

Using a transmit value above 1.0 just extends the logic... The colors seen
through the pigment will *spread out* from your specified rgb color. And the
brighter the transmit value, the more the colors spread out.

If you use rgb 0.0 transmit 2.0 then all colors will spread out from rgb
0.0, that is, colors above 0.0 get brighter and colors below 0.0 get darker
(but you usually don't have negative colors in your scene).

If you use rgb 1.0 transmit 2.0 then all colors will spread out from rgb
1.0, that is, colors below 1.0 get darker and colors above 1.0 get brighter
(but they'll just appear to still be white).

If you use rgb 0.5 transmit 2.0 then all colors will spread out from rgb
0.5, that is, colors below 0.5 get darker and colors above 0.5 get brighter.
This is in effect a contrast filter that gives 2x contrast.

The trick works independently on red green and blue, so you can also get
special effects by using non-gray colors.

Rune
-- 
3D images and anims, include files, tutorials and more:
rune|vision:  http://runevision.com
POV-Ray Ring: http://webring.povray.co.uk

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