Extracting a subject from a busy photograph often results into an extraneous effort, especially when there’s hair, feathers, or the like, involved. Masking a simple geometric shape like a circle is one thing, but capturing all the detail of real-life subjects can take you the better of your day/evening.
When Photoshop CS5 launched, I must admit I had difficulties identifying the various new features. This is undoubtedly caused by the immense feature-set resident in PS, aggravated by the archaic menu-based UI it drags along (which, in my opinion, is in dire need of a rework, perhaps one akin to the Microsoft Office Ribbon).
Users of previous versions of Photoshop may recall a filter called ‘Extract’. This was the tool you would use to carefully (and destructively) extract subjects from images. This tool has made room (it’s literally been yanked from Photoshop) for newer and superior approaches, of which ‘Refine Edges/Mask’ is the most prominent one.
The way it works is to make a selection with the masking tools you’re used to from previous versions, or one of the new ones in CS5, and refine the edges using the menu ‘Selected > Refine Edges’ (or ‘Selection > Refine Mask’ if a mask is selected). This feature was present in CS4, but has been improved greatly in CS5.
For selections I like to add a Layer Mask to a layer and paint my selection with one of the brushes.