>Should we also look at implementing some other stain separations?

That could be done quite easily, but a more generic solution could be that the user gives the stain separation matrix which would break the conventions of the color module (you basically don't choose your matrix when you convert from rgb to La*b* or any other colorspace). Would you then prefer to put these function into another module?

> Nice--what are we looking at here?

This is colon tissue marked anti-FHL2 with DAB staining and Haematoxylin counter staining.

>Yes, a better naming would be good, but let's keep it public. Also, we may want to use a smaller image, if you have one available, but it's not a big deal.

I agree the naming is not well chosen. I'll put a more explicit one. However, I don't see why the function should be private: it's a nice to have example for people working on histology images. For the image, I could just crop the image and keep the region around the glands.