1. A method of automatically enhancing a digital image having a smooth-boundaried foreground object, comprising: processing the image via gradient-based background segmentation at a first scale to generate a first mask, having a first accuracy, used to generate a first background of the image which includes at least a portion of the smooth-boundaried foreground object; processing the first background via gradient-based background segmentation at a smaller second scale to generate a second mask, having a greater second accuracy, used with the first mask to generate a second background of the image which substantially excludes the smooth-boundaried foreground object; enhancing the image using the second background so as to preserve the smooth-boundaried foreground object; and outputting the enhanced image.