Am 4/2/2021 um 4:23 schrieb Kenneth:
> 
> This made me re-think one of my old questions regarding basic rgb-to-srgb color
> conversions in a POV-ray scene, that's still a bit of a mystery: Do I understand
> correctly now that *any* srgb conversion of a *multiplied* rgb color has the
> same kind of hue distortion-- even when the multiplier is <= 1.0? I assume so,
> but I want to clearly understand it. For example, given rgb <.7,.8,.9>*.4, the
> *wrong* way to do the conversion would be  srgb <.7,.8,.9>*.4 ... and the
> correct way (one way) would be to #declare TEMP = srgb <.7,.8,.9> and *then*
> multiply TEMP*.4
> 

Just to make it clear - as I have the impression you do misunderstand 
the srgb keyword: it is NOT about rgb-to-srgb conversion, it is the 
other way around. The srgb keyword is for converting a given sRGB color 
value to a linear RGB color.

> Long ago, either you or Clipka had given a different kind of example of this,
> but used an rgb value of something like
>             rgb <104,230,75>/255
> and then warned about naively converting that to srgb with a simple
>            srgb <104,230,75>/255
> 

Well, well well... here goes the same as with my response to Thomas. I'm 
certain that Christoph or myself never warned about /this/ particular 
usage. Quite the opposite: this is exactly what the srgb keyword was 
meant for. You have a byte values (either from a color picker or from 
some web color), and the division by 255 transforms this byte value into 
the 0..1 range. The result is still a sRGB value and prefixing this with 
the srgb keyword simply tells POV-Ray to treat it as such and internally 
converts it to a linear RGB value.

-Ive

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