1 .) A method for reconstructing an image of an object, the image comprising a plurality of image elements, the method comprising: accessing image data associated with the plurality of image elements; applying a first algorithm to the plurality of image elements; selecting a spatially non-homogenous set of the plurality of image elements; and applying an iterative algorithm to the set of image elements to reduce an amount of time necessary for reconstructing the image, or to improve an image quality at a fixed computation time, or both.