If you have an object that has been cut out with a mask you can use the color decontamination feature.
What is matting in photoshop.
Matting is a menu item in the layer menu used to edit pixels on the fringe of an image or new layer.
Most images don t really have a need to use these tools but when they can be used it s great to know they are there.
For example when a section of one image is moved to another anti aliasing can create.
This video is available free for everyone.
Simply select the layer with the fringe on it and go layer matting defringe and typically i defringe between 1 3 pixels depending on how much fringe it there.
This photoshop tutorial video on how to use the defringe white matting and black matting tools.