Map angle to RGB color

Question

This video shows what I think is a great visualization of gradient angle by mapping angle (in [-pi,pi]) to RGB color:

I would like to know if it is possible in OpenCV C++ to map a floating point value angle , whose range is -M_PI to M_PI , to an RGB value in some preset colorwheel. Thank you!

Answer 1

Look up hsv to rgb. H, or hue, is the angle you are looking for. You probably want full saturated values with maximum value, but if you turn s and v down a notch, the coding will look less artificial and computery.

Answer 2

Can you calculate this directly from the angle and the edge strength?

red   = edgeStrength * sin(angle);
green = edgeStrength * sin(angle + 2*M_PI / 3.); // + 60°
blue  = edgeStrength * sin(angle + 4*M_PI / 3.); // + 120°