1. A method of classifying an object, comprising: a first phase comprising application of an object classifier to the object to obtain first object class probabilities of the object belonging to respective different object classes, and application of a material classifier to the object to obtain first material class probabilities of a material type of the object belonging to respective different material classes; and a second phase comprising application of an interdependent object/material classifier to the first object probabilities to obtain further object class probabilities, and to the first material class probabilities to obtain further material class probabilities, so as to classify the object class and to classify the material type of the object, wherein, the interdependent object/material classifier performs multiple iterations of calculating the further object class probabilities and multiple iterations of calculating the further material class probabilities, and wherein, an immediately preceding calculated prior further object class probability is included in a next iteration of calculating a further material class probability, and an immediately preceding calculated prior further material class probability is included in a next iteration of calculating a further object class probability.