Method of classification of tagged material in a set of tomographic images of colorectal region

A method of classification of image portions corresponding to fecal residues from a tomographic image of a colorectal region, which comprises a plurality of voxels (2) each having a predetermined intensity value and which shows at least one portion of colon (6 a, 6 b, 6 c, 6 d) comprising at least one area of tagged material (10). The area of tagged material (10) comprises at least one area of fecal residue (10 a) and at least one area of tissue affected by tagging (10 b). The image further comprises at least one area of air (8) which comprises an area of pure air (8 a) not influenced by the fecal residues. The method comprises the operations of identifying (100), on the basis of a predetermined identification criterion based on the intensity values, above-threshold connected regions comprising connected voxels (2) and identifying, within the above-threshold connected regions, a plurality of connected regions of tagged material comprising voxels (2) representing the area of tagged material (10). The method further comprises the operation of classifying (104) each plurality of connected regions of tagged material on the basis of specific classification comparison criteria for each connected region, in such a way as to identify voxels (20) corresponding to the area of fecal residue (10 a) and voxels (2) corresponding to the area of tissue affected by tagging (10 b).