A method and a device for classifying samples of an image, each sample having a respective sample value the method comprising repartition of each of the samples into a plurality of index classes, wherein the index class allocated to each sample is determined in dependence upon the sample value of the said sample with respect to the sample values of first neighboring samples of said sample according to a given direction and further in respect to the sample values of the first neighboring samples with respect to the sample values of samples neighboring the first neighboring samples according to the said given direction. Processing each sample according to the respective allocated index class.