Keep black lines, make other colours transparent

Question

Here is a sample image :

The white background is actually transparent.

I'd like to keep only the black lines and surfaces, and make all other colours transparent.

Is it possible to do this ?

I'm using Pixelmator, but a photoshop process will be fine !

Answer 1

Basically, the light colors are easier to get rid of with simple contrast adjustment, the dark blues are probably gonna be harder work.

But since this is a comic, it was probably inked first and then colored later. So maybe just ask the publisher of André Franquin for an uncolored version?