Patent ID: 7592977

Claim:
An image processing method of a plasma display device for expressing a gray level by a combination of a plurality of subfields divided from a frame of an input video signal, the image processing method comprising: detecting a moving image block and a still image block from the input video signal; determining output gray levels corresponding to original gray levels of the detected still image block such that respective output gray levels corresponding to the original gray levels of the detected still image block satisfy a first condition that the number of consecutive non-lighting subfields is less than or equal to L among subfields driven previously to a last turn-on subfield of the corresponding output gray levels; determining output gray levels corresponding to original gray levels of the detected moving image block such that respective output gray levels corresponding to original gray levels of the detected moving image block satisfy a second condition that a number of consecutive non-lighting subfields is less than or equal to M, and a third condition that a total number of non-lighting subfields is less than or equal to N among subfields driven previously to a last turn-on subfield of the corresponding output gray levels; and displaying the determined output gray levels of the detected still image block and moving image on the plasma display device; wherein when at least one of the original gray levels of the still image block does not satisfy the first condition, the output gray level corresponding to the at least one of the original gray levels of the still image block is determined by selecting at least two output gray level candidates satisfying the first condition and by applying a dithering algorithm to the selected output gray level candidates, and wherein when at least one of the original gray levels of the moving image block does not satisfy at least one of the second condition and the third condition, the output gray level corresponding to the at least one of the original gray levels of the moving image block is determined by selecting at least two output gray level candidates satisfying both of the second and third conditions and by applying a dithering algorithm to the selected output gray level candidates.