How can I cut out a foreground object, e.g. a person, from one picture and superimpose it onto a new background without making the edges look bad?
The problem I've come across is that if I have for example a white background and a dark blue object, there are some pixels at the edge of the object that are various lighter blue shades. If it were a black background instead, those pixels should be darker shades of blue instead of lighter; how can I change them appropriately when I want to replace the background? It's not too hard to fix this when I just have two colours, but what about when the imaged is varied, like with a photo of a person outdoors? I've tried blurring the edges of the object into the background, which is not awful but the edges don't look crisp enough.
I use Photoshop CS5 if there's a specific PS way of doing this.