PURPOSE: A noise removal method of an image is provided to accurately detect noise of a horizontal line through an edge of a horizontal direction, thereby effectively removing the noise of the horizontal line. CONSTITUTION: An NVS(Night Vision System) applies a horizontal edge detection filter to a pixel area among image data and detects an edge of a horizontal direction. The NVS determines existence of noise of a horizontal line of the pixel area through the edge of the horizontal direction. The NVS calculates the number of pixels which is determined as the noise of the horizontal line for lines of the horizontal direction of the image data. The NVS applies a low-pass filter to a line of the horizontal line having the noise and removes the noise of the horizontal line. [Reference numerals] (AA) Start; (BB) Extract a 7 × 1 constant pixel region; (CC) Calculate an absolute differential value of the constant pixel region due to a horizontal edge detection filter; (DD) Calculated absolute differential value > First threshold value ?; (EE) Determine noise of a horizontal line; (FF) Accumulate the number of pixels determined by the horizontal line noise by line; (GG) Accumulated value > Second threshold value ?; (HH) Calculate an average brightness value; (II) Average brightness value > Third threshold value ?; (JJ) Process an LPF in a vertical direction; (KK) End
