Please, I would like to code a color toner in VEX, to generate @Cd attribute in SOPs. Similar to the After Effects CC Toner (image attached).

Is this plan correct, as regards mathematics and color theory, please?

1) convert output colors to HSV with rgbtohsv()
2) use spline() to output an interpolated Hue
3) use spline() to output an interpolated Saturation
4) use spline() to output an interpolated Value
5) convert the HSV back to RGB with hsvtorgb() and output that RGB

As regards the spline(), the "monotonecubic" interpolation should be fine?