where the peaks are in terms of the number of transitions per byte and is indicative of the size and frequency of runs of on or off pixels in the image the transition array provides a measure of the clustering of the dots of the image at a fine level of detail thereby enabling an even better classification of the dither type of the image when combined with the average number of transitions per byte once the aforesaid values have been determined a compression procedure is assigned box 48 based upon the type of dither determined for instance it has been found that the lempel ziv compression procedure operates best upon text and line art and that text and line art are indicated by one peak in the transition array accompanied by less than 1 3 transitions per byte for bytes having transitions by contrast a lossy compression procedure is indicated for use when an error diffusion dither is found an error diffusion dither is indicated by more than one peak in the transition array where peaks are at even numbers in the array either 2 4 6 or 8 combined with an average number of transitions per byte of bytes with transitions that is greater than 2 5 per byte any other type of dither i e cluster fine cluster vertical line is best handled by cache based predictor compression these classifications are found in table 1 below table 1__________________________________________________________________________ local maxima in avg trans byte ofdither transition array bytes w trans compression__________________________________________________________________________text amp line art 1 avg lt 1.