[Asooka]

If you blend values in linear space, you'll linearly interpolate from the starting physical intensity to the ending physical intensity. This is a very reasonable default, corresponding to an objective physical measure. Also it makes your gradient appear roughly the same to people with reduced colour perception. Other modes would be useful too, maybe something that goes through HSB colour space, but I suspect designers would find it easier to design their desired gradient in a program of their choosing that then outputs a piecewise linear approximation.