Systems, methods, and computer-readable storage media for resizing images using seam carving techniques may access a pre-computed retargeting matrix for an input image that associates each pixel of the input image with a cost order of a horizontal and/or vertical seam of which the pixel is a part. The retargeting matrix may be divided into sub-matrices corresponding to horizontal or vertical strips of the image, in the direction of a desired seam carving operation, for parallel processing on multiple processors or threads thereof. The retargeting matrix and/or sub-matrices may be usable in performing one or more reduction or expansion operations on the input image without re-computation of the matrices between retargeting iterations. The methods may include pre-computing the retargeting matrix and/or sub-matrices. The methods may be implemented as stand-alone applications or as program instructions implementing components of a graphics application, executable by a CPU and/or GPU configured for parallel processing.