Patent ID: 6535254
Filing Date: 2003-03-18
Classification: H04N

Abstract:
The method for reducing noise in a video signal that includes a plurality of video frames of digitized video information represented in a plurality of pixels, the method comprising the steps of:storing a current video frame and a plurality of temporally adjacent video frames; selecting from the current video frame a current frame portion comprising a current pixel and at least one pixel spatially adjacent to the current pixel; selecting from the temporally adjacent video frames temporally adjacent frame portions comprising a pixel or pixels that spatially corresponds to the pixels of the current frame portion; determining the luminance value of each pixel in said current frame portion and said adjacent frame portions; determining the average luminance values of said current frame portion and said spatially adjacent frame portions; determining and comparing to a first threshold value the absolute value of the difference between the average luminance of said current frame portions and the average luminance of said adjacent frame portion; if the absolute value of the luminance difference exceeds said first threshold value, assuming there is a local scene change in the video information between said current frame portion and said adjacent frame portion; else determining and comparing to a second threshold value the absolute values of the difference between the values of a color component of said current pixel and the corresponding pixel of said adjacent frame portion; if the absolute value of the color component value difference exceeds said second threshold value, assuming there is a local scene change in the video information between said current frame portion and said adjacent frame portion; else assuming that there is no local scene change between said current frame portion and said adjacent frame portion; selecting an even number exceeding or equaling zero of adjacent frame portions considered to involve no local scene change in relation to said current frame portion; selecting the video information from a pixel that is probable to have equal predecessor and/or successors by: comparing the luminance values of said current pixel and the corresponding pixels in said selected adjacent frame portions and selecting the video information of the pixel having the median value of said luminance values; assigning said selected video information to the current pixel to thereby produce a video frame wherein noise has been reduced.