A processor is disposed in a display device and is configured to perform following operations: calculating a total coupling coefficient for a (N−1)th frame according to input data, in which N is a positive integer greater than 1; calculating a coupling coefficient difference value of two adjacent lines for a Nth frame according to the input data; generating a first compensation value for a target sub-pixel according to the coupling coefficient difference value and target input data of the target sub-pixel; generating a second compensation value for the target sub-pixel according to the first compensation value and the total coupling coefficient; generating an output data for the target sub-pixel according to the target input data and the second compensation value; and controlling a display panel in the display device to display a final image according to the output data.