Because it's black you would be smarter applying a reverse mesh.Negating the black first.

Here I've just
>duplicate layer
>brightness and contrast %100 to black/white
>deleted white
>inverted image
This gives me the underwear area as a white block
>apply as overlay
overlaying the white to negate the black, probably how the artist applied the underwear in the first place

20 second attempt but this is just to explain