Understanding color ramp modes

In today’s tip we’re going to take a clos­er look at the good old col­or ramp node.

The col­or ramp node in (ramp set­ting in BI) lets you map an image or tex­ture to a col­or gra­di­ent. The gra­di­ent is defined by 2 or more col­or stops. How the col­or in each stop tran­si­tions into the next is defined by the mode. The dif­fer­ent modes give the ramp a lot of flex­i­bil­i­ty and pow­er, though we don’t often talk about them.

Let’s check how the dif­fer­ent modes work by check­ing them on a sim­ple voronoi tex­ture. Don’t wor­ry, I won’t go into any of the math behind these because my brain melt­ed from just look­ing at the equa­tions. I’ll include the Wikipedia links below if you want to inves­ti­gate further.

Linear

The default mode. Full stop col­or hap­pens only in a small part and tran­si­tions quick­ly into the next. The mid­dle point between two col­or stops has a 50/50 mix of both colors.

Useful when con­trol­ling a fres­nel and try­ing to keep a thin, hard edge on the sides where the effect is the strongest.

Check Linear Equations in Wikipedia

Ease

This mode eas­es the ramp by a qua­drat­ic equation.

Transitions are smoother than lin­ear since each stop’s influ­ence is more spread out. That also means that you get more full stop color.

Ease is the mode I use the most, since the tran­si­tions are smoother than lin­ear but not too much.

Quadratic Equation in Wikipedia

B‑Spline

This is the smoothest mode. You nev­er see full stop col­or here, instead col­ors flow into com­plete­ly each other.

The B‑spline mode is great to soft­en masks and tex­tures. Keep in mind, how­ev­er, that it can’t soft­en an image that has no inter­me­di­ate val­ues between col­ors (some­thing crunched by the con­stant mode, for instance).

B‑splines in Wikipedia

Cardinal

Cardinal gives a larg­er tran­si­tion with more amount of full stop color.

I haven’t found many uses for car­di­nal so far, but if you find your­self look­ing for a soft­er ease ramp you should try this mode.

I couldn’t find the exact equa­tion for this, but this post from Harder, bet­ter, faster, stronger might give you a hint. 

Constant

Sometimes peo­ple try to crunch val­ues by push­ing them togeth­er in the ramp with the default val­ue. But that’s not always the best option, the prop­er way is to use the con­stant mode.

This mode splits the ramp in absolute val­ues at each stop. Not only you get the same effect with one click, but you can also move the stops to tweak the effect. Constant mode is basi­cal­ly like using the “Round” oper­a­tion from the Math node, but more versatile.

There’s no par­tic­u­lar equa­tion in this mode. Each stop cov­ers the ramp until the next with­out transitions.

That cov­ers the cur­rent modes as for Blender 2.74. I Hope you’ve found this use­ful, stay tuned for more tips!