I have been trying to use the Selection Brush tool, to put an object from a photo i have taken, on to a white background. But after pressing "refine" and putting the white background, som square lines seem to appear (Some times they are white, other times they are black). It has happened before when using it and i can´t seem to make them disappear. It is possible for me to erase the lines with the erase brush tool, but it takes too much time to do every time.
What am i doing wrong, and how can i remove them?