1. A method for filtering a digital image comprising a first plurality of pixels, the method comprising: segmenting the first 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; 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; and filtering the digital image by applying the image transfer function to each of the first plurality of pixels.