Remove selective cast/stain

[The_JinJ]

Hi all

I'm looking for ways to remove selective areas of red stain/cast on an image.

I can remove an overall red cast using inverted average colour but short of converting to B&W (using the undamaged red channel) and recolouring or cloning areas I can't figure out a way to do this.

A thought was using channels somehow, maybe as a mask, as the red channel has no damage, green and blue do.

Here's an image with the general red cast removed on the left and the remaining stains on the right.



Any help appreciated!