Gimp: B&W and color

Granit

Ok, let's say you have a picture, you turn it B&W and want to keep some of it in color.

I have a way of doing it with the Gimp, but there must be another one, maybe easier.

Here is how I do it:

-Copy the layer, to have two identical picture on top another
-Turn the foreground layer in B&W
-Erase to backgroung the region I want in color

This is what I did bellow, any other way?

Pupator

I would think you could select the area you want to remain colored and desaturate the rest.

Granit

Yes that almost works too.

But example the picture shown, i had to select all the colored numbers, that made a big zone, I INVERTED and desaturated the rest.

But the white in that big zone (not desaturated) and the white that got desaturated was not the same, end recult was that the zone was sticking out, not just the letters.

Doing the letters one by one and desaturating them was also difficult because selecting all their edges would have taken for ever.