1. A system, comprising: one or more processors; and a memory coupled to the one or more processors and storing program instructions executable by the one or more processors to implement: accessing data representing an image; for each of one or more previously defined regions of the image, wherein each of the one or more regions is less than all of the image: determining a respective energy value for each pixel of the region dependent on a value associated with each pixel; and performing a resizing operation on the region to produce a resized version of the region dependent on the respective energy values of the pixels of the region, wherein the resizing operation is performed independent of any resizing operations performed on any other portion of the image, and wherein the resizing operation does not affect any other portion of the image; and producing a resized version of the image comprising the resized versions of the one or more regions and any unchanged portions of the image.