Ramp

Ramp is what grown-ups call a gradient. The Ramp node of Nuke give a butter-smooth gradient that is best used to mask off color operations and suchlike.

Ramp type

The way that the black blends into the white is controlled by the 'type' parameter. This is probably the most important parameter of the Ramp node. The 'type' values are:

linear

The ramp changes in a linear fashion, but also in linear colour space. As it is in linear space, it will appear weighted towards one end of the ramp.

plinear

This provides a perceptually linear ramp (unlike linear, which is mathematically linear).

smooth0

This weights white at one end of the ramp.

smooth1

This ramps white at the other end of the ramp.

smooth

the ramp color gradually eases into both ends. This means colors in the point 0 and point 1 ends are spread wider than colors in the center of the ramp.

The Ramp node can only ramp from one colour to zero (black). The Rectangle and Radial nodes both come with an optional embedded radials (in their 'color' tab). Using these, a ramp can be made that ramps from one color to another.