1. A method of retargeting a digital original image to a digital target image, said method comprising: (a) accessing said original image, wherein the size of at least one dimension of said original image is different than the size of the corresponding one dimension in said target image, and a scaling factor relates the size of said one dimension of said original image to the size of said corresponding one dimension in said target image; (b) constructing an image saliency of said original image; (c) filtering the image saliency under the guidance of said original image to produce an importance map, S Imp , that matches pixels to salient structures in said original image; (d) estimating a shift-map gradient G according to said scaling factor and under the constraint of said importance map S Imp , wherein pixels that are matched to salient structures are assigned a consistently distributed gradient; (e) defining a shift-map M from said shift-map gradient G, wherein said shift-map M estimates pixel shifts from said original image to said target image; and (f) applying said shift-map M to said original image to construct said target image.