Recently I was reading about Perlin Noise (here too) and they mentioned using S Curves to blend random numbers togther in a more natural manner. The effect of using S Curves is that values don’t change as fast at either end of the range.

I already had code that did linear color blending. I added a routine that does color blending using an S Curve and generated images to show the effect.

The first image is a linear blend, and the 2nd uses S Curves:

The red curve here is the S curve, and the straight line is a linear change:

For related info see Logisitic Functions