Are there any standard algorithms for this? It seems "reasonable" that what it "should" do is look for a bright red colour and change that to black. It might be easier to do that using luminance values though. (And looking at the luminance and Cr / Cb values.)
Here is a possible process:
-look for the bright red colour
-remove the red layer from the image at this location
-keep the green/blue layers, and replace the red one by one of the other two.
Just an idea, I use this process (with a manual selection of the area
to treat)
to solve the problem, and usually it works very well.
François