cutting out heads in photoshop

^ see right there how the people's heads are cut out and then posted on the background of their choice.

how is this done? simple polygon lasso?

doesn't the picture of the face have to be TAKEN on a WHITE background?

thanks in advance

The original can have ANY background, its alot easier to isolate the subject if they are on a solid color background but they can be extracted from any background if you take your time.

Isolating the subject to pull them from the background can be done several different ways but the best and by far the most precise is with the pen tool. You draw a path about 1 pixel inside the edge of your subject.