The idea of a black and white strip that uses colour in only one (or two in this case) which would be a rainbow. As such the idea of someone studying colour theory seemed like an obvious fit.

Basic sketches

The problem with this is that it would look quite empty, so I decided to add texture through cross-hatching.

Refined Sketches

Linework and Cross hatching

Colours

I decided to see if adding more colour to the linework and cross-hatch, using mostly black and then increasing the amount of colour with each subsequent. 

Final