Patent ID: 7180480

Claim:
A method of removing false contours in a pulse number modulation (PNM) digital display device, in which predetermined pixel data processed in a current frame (hereinafter, referred to as input data) is compared with corresponding pixel data in a previous frame (hereinafter, referred to as comparison data), wherein it is determined, based on a result of the comparison, whether or not false contours have occurred, and the input data is modulated and output so that the false contours are removed, the method comprising: a) comparing the input data with the comparison data and calculating a plurality of possible output data in consideration of an index error between the input data and error-diffused input data so that the false contours are removed, the error-diffused input data being obtained by diffusing a quantization error that has occurred in pixels adjacent to the input data in the current frame; b) detecting an index error between the input data and the error-diffused input data; c) selecting one from among the plurality of possible output data obtained in a) in consideration of the index error detected in b); and d) sending the selected output data to a display driving unit of said digital display device to display the input data without fuse contours.