1. A method of enhancing an image of an object so as to increase the visibility in the image of at least one structure within the object, wherein the image is characterized by a plurality of pixels, each pixel having an associated pixel value that represents the image intensity of a corresponding unit volume of the object, the method comprising: a) selecting at least a first neighborhood and a second neighborhood within the image, b) constructing an operator configured to select, within the first and second neighborhoods, one or more pixels having an optimal pixel value, and to eliminate the remaining pixels in the neighborhoods; and c) applying the operator to the selected neighborhoods so that only the pixels having the optimal pixel values remain in the selected neighborhoods, and the remaining pixels in the selected neighborhoods are eliminated.