1. A system for selecting a pixel block within an image frame, comprising: a pixel block processor for, selecting a pixel block of a predetermined size within an image frame encompassing a plurality of pixel blocks; determining boundaries of an extended pixel block encompassing the selected pixel block and additional pixels of an overlapped region; deriving statistical information for said selected pixel block and said overlapped region; and selecting one of said selected pixel block and said extended pixel block in response to said derived statistical information.