1. A method for defining a selection mask associated with a source image, the method comprising: displaying a selection cursor over the source image, the selection cursor having an interior region and a peripheral region; and locating an initial position of a selection mask boundary in a portion of the source image that is overlaid by the peripheral region of the selection cursor, wherein the initial position of the selection mask boundary is at least partially based on a boundary that is detected as a result of selectively applying a boundary detection algorithm to a sub-region of the source image.