[Bf-funboard] A needed node.

David Jeske davidj at gmail.com
Tue Jul 2 07:13:07 CEST 2013

continuing on the topic of "random color" vs "pick random"....

I think the mathematical reason "truly random" colors like this are going
to tend towards middy-middle-grounds, is that statistically, it's going to
be unlikely to get colors where two of the channels both picked low values.

To get good "artistic" randomly selected colors, I think there needs to be
a palette table in there somewhere to stay away from muddy randomness. If
more limited-variance is desired, random values can be plugged into a
hue/saturation adjuster.

Here is an example, both using exactly the same RGBCurves and random

This first version uses "mathematically random color channels", with a
"random gamma factor"


This version uses a "random 5-color pallette selection", with a "random
gamma factor"...


The difference is subtle but important.. The "truly random" version has
muddy mauve and annoying colors which are hard to get rid of. The palette
colors are easy to control, even with a random gamma factor applied to
provide more variance. All IMHO of course.

After these experiments I'm thinking about two things:

1) would it be nice to have a "random value" node which is easier to use
than the modulo node? (I'm thinking yes...since these magical floating
point divides don't have good mathematical distribution)

2) would it be nice to have a slightly different mode for ColorRamp to make
large palettes easier?   (I'm thinking yes, but could go either way... My
palette of 5 was easy. Editing a palette of ~30 while keeping it evenly
spaced would be annoying, but an easy addon could help.)

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