Compute the distance between two colours.

Input parameters:

1. Ca → First colour for computing the distance.
2. Cb → Second colour for computing the distance.
3. M → Distance metric to be used.
   • 0 → RGB Linear
   • 1 → RGB Standard
   • 2 → HSV (value)
   • 3 → HSL (lightness)
   • 4 → H*SP (luminance)
   • 5 → Sinusoidal
   • 6 → CIE ΔE₀₀

Output parameters:

1. D → Distance between colours.