Cousin Ricky <ric### [at] yahoocom> wrote:
> On 2025-08-12 15:50 (-4), Clarence1898 wrote:
> > Many years ago my grandchildren loved to play with this when they came over.  I
> > thought it would be fun to model it in povray.  One problem I had was the orange
> > color of the arm was not bright enough.  I could never get it bright enough
> > until I learned you could specify color values greater than one.  Using
> > rgb<2.0,0.5,0.0> finally matched the real object.
>
> Assuming you haven't changed the default finish diffuse, this works out
> to a final color of rgb <1.2, 0.3, 0.0>.  Counterintuitively, I have
> found that this color is quite physically possible in the real world,
> given the limitations of the sRGB color system used by most computer
> screens.
>
> The image spectral_orange.png shows some spectral power distributions
> for oranges and adjacent colors.  As you can see from the negative
> channel values, all of these colors are too saturated to be shown
> accurately on a standard computer screen; what you're seeing is a
> desaturated approximation. But relevantly, all but the first and last
> colors have red values greater than one, even though they never reflect
> more light than they receive at any wavelength.  As a result, POV-Ray
> clips the red values.
>
> The image spectral_orange-gld.png uses UberPOV to show the true
> luminance of the oranges, but at the expense of saturation.  Within the
> limitations of the sRGB color system, something has to give.
>
> I would just be careful not to do this with metallic reflection, as that
> can cause problems.  With metallic reflection, you really would be
> reflecting more light than you receive.

This is the texture I used:

#declare tPlasticOrange =
  texture {
    pigment{rgb <2.000, 0.50, 0.0>}
    finish {
      ambient 0.1
      diffuse 0.6
      specular 0.3
      }
    }

It was derived by pure trial and error.  Until I increased the red value above 1
I couldn't get the color bright enough to match the real object.  I took a
picture of the object and adjusted the color and finish until it matched.  I
will keep in mind not to do that with metals.  Though now I am tempted to try it
just to see what happens.

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