1. A method of processing a medical image comprising an organ, the method comprising: a) obtaining a medical image; b) automatically estimating one or more organ intensity characteristics in the image, from contents of a region of the image that appears to correspond, at least in part, to at least a portion of the organ; c) providing a plurality of sets of organ intensity characteristics, each set a different example of possible intensity characteristics of the organ; d) choosing one of the plurality of sets, that has organ intensity characteristics that provide a better match than one or more other sets to the estimated organ intensity characteristics of the image; e) setting values of one or more image processing parameters based on the organ intensity characteristics of the chosen set; and f) automatically processing the image using said values of image processing parameters.