1. A method to filter a digital image comprising a plurality of pixels, the method comprising: segmenting the plurality of pixels into a first plurality of regions; computing a first plurality of regional histograms by calculating a regional histogram corresponding to each region in the first plurality of regions, wherein the regional histogram is a three-dimensional histogram; computing a first plurality of regional transfer functions by calculating for each region in the first plurality of regions a regional transfer function comprising a convolution of the corresponding regional histogram with a first convolution kernel; deriving an image transfer function by interpolation of two or more of the first plurality of regional transfer functions; filtering the digital image by applying the image transfer function to each of the plurality of pixels to generate a filtered digital image; and causing the filtered digital image to be displayed.