1. A method for registering a deformable image to a fixed image, comprising steps: acquiring the deformable image; acquiring the fixed image; generating a multi-resolution multi-level image pyramid for the deformable image; generating a multi-resolution multi-level image pyramid for the fixed image; processing levels of the multi-resolution multi-level image pyramids in a coarse to fine order, and for each deformable image at each level, and for each fixed image at each level: partitioning the deformable image into overlapping blocks; labeling each block with a label, wherein the labeling for each block further comprises: solving, iteratively and in parallel until a termination condition is reached, a binary maximum flow problem within α-expansion for each block and performing boundary fusion for the blocks; registering each block according to the labels to form the fixed image, wherein the steps are performed in multiple processors.