This is caused by the choice of the nearest point on the foreground convex hull as the final color of a pixel, rather than using a line of best fit through the colors of the neighboring pixels to pick a point on the foreground convex hull which is closest to that line.
This is caused by the choice of the nearest point on the foreground convex hull as the final color of a pixel, rather than using a line of best fit through the colors of the neighboring pixels to pick a point on the foreground convex hull which is closest to that line.