1. A digital image filtering method comprising the steps of: selecting a first matrix of a plurality of pixels from a digital image to be displayed; analysing the luminosity values of each of the pixels in the pixel matrix and calculating the luminosity difference between the maximum and minimum luminosity values thereof; classifying the central pixel of the matrix according to the luminosity difference in comparison to a predetermined threshold luminosity value; repeating the above selection, analysis and classification for each of the pixels of the image in turn; and selecting a target pixel from the classified pixels for further analysis, said further analysis comprising the steps of: selecting a second pixel matrix of which the target pixel is the central pixel; analysing the classification of the pixels surrounding the target pixel in the second matrix; and filtering the target pixel to an extent dependent upon the classification analysis.