The concepts of automatic detection of foreground and background seeds are sketched in (A to C). Foreground seeds are located based on the encoder function (i.e., thresholding) given in (A to B). Foreground seeds are allocated in the high uptake areas, and their neighbors are searched for background regions (B). Foreground and background seeds are propagated into MR correspondence (C). Random walk delineation is conducted by the guidance of foreground and background seeds.