On “b_min” computation.

[KelSolaar]

I reckon that if we pass b_min directly, we should so it everywhere consistently with a comment explaining what it is or we should compute it explicitly.

It is also worth noting that Colour's code already normalises the white balance multipliers, so b_min is not even strictly required.

[nick-shaw]

Indeed. Since b_min is currently always 1.0, there is a good argument for removing it entirely. Unless we remove the normalisation from Colour, or make it optional.