1. A method for blending resembling blocks, performed by a processing unit, comprising: obtaining a frame from a frame buffer, wherein the frame is generated by a camera module comprising an image sensor to detect the frame; determining a target block of the frame to be fused; determining a search window for the target block and obtaining m neighboring blocks from the search window; grouping the m neighboring blocks with the same distances from the target block into a plurality of sub-groups; obtaining k groups of the neighboring blocks by merging the sub-groups, wherein each group has the same quantity of the neighboring blocks as that of the other groups, and the averaged distance of the neighboring blocks of each group are close; calculating a difference between the target block and each neighboring block; selecting at least one resembling block from the neighboring blocks of each group of the k groups according to the differences; calculating a weighting for each resembling block; fusing each pixel value of the target block with a corresponding pixel value of each of the resembling blocks according to the weighting; and updating the pixel values of the target block of the frame according to a fusion result.