colortriangle | HSL based color picker | Datepicker library

To answer the first question, there are many things that should be noted.

To start with, the only way that a single value can represent a color is using a colormap, which maps a scalar to a color. However, the Maxwell triangle cannot be reduced to a single value.

That does not mean that the maxwell triangle cannot be used as a kind of 3D colormap, mapping 3 values to a color. In fact it is quite natural to do, because the Maxwell uses 3 values a, b and c so that the color can be represented in RGB coordinates as (a,b,c). The only thing missing is the normalization.

In the link provided, the Maxwell triangle is defined such that a+b+c=1. However, matplotlib accepts RGB coordinates as 3 floats between 0 and 1, where white is obvsiously 1,1,1, instead of 1/3,1/3,1/3. Thus, each i,j will have three values that must be converted to 3 floats between 0 and 1 taking this into account.

Therefore, instead of normalizing dividing by the sum (to get a+b+c=1) we have to normalize dividing by the maximum value of each trio.

Eventually, the resulting image can be shown using imshow.