inpainting is global average color, not local

[camilleg]

With an input and mask of the same format as data/*.png, the inpainted result is roughly the global average, not nearly the average of each local neighborhood. The attached results are typical for 1 to 1000 iterations. I would have expected the inpainted masked "H" to be mostly red at left, mostly blue at right, not purple everywhere.
Ubuntu 22.04.3 with that distro's current opencv packages.
This may be a duplicate of issue #4 .