Method of image noise reduction
View Patent ↗A method of noise reduction in an image obtained with the use of TV camera comprising a generation of a frame video flow out of frame groups, having timing interdependency; a generation of an image out of output frame series obtained by means of processing of the said frame groups by the use of averaging closely adjacent pixel values in at least one group of frames; and the use of average values considering weight coefficients to form an output frame.
1. A method of reducing noise in a video produced using a TV camera, the method comprising
generating in a video channel a video flow with at least one video frame group, the at least one video frame group comprising an odd number of 2N+1 video frames having time interdependence,
wherein N is ≧1, and
wherein the video frame to be processed for reducing noise to produce an output video frame is a middle video frame in the at least one video frame group, and wherein remaining video frames in the at least one video frame group are N pairs of video frames juxtaposed time-symmetrically with respect to the middle video frame;
determining a pixel value of a corresponding pixel positioned in each of the 2N+1 video frames;
calculating for each pair of video frames an average pixel value for corresponding pixels positioned in the video frames of the pair;
calculating for each pair of video frames an absolute value of a difference between the calculated average pixel value and the determined pixel value of a corresponding pixel in the middle frame,
calculating for each video frame of each pair an absolute value of a difference between the determined pixel value of a corresponding pixel positioned in a pair of video frames and the determined pixel value of a corresponding pixel positioned in the middle video frame;
determining a minimal of all said absolute values; and
selecting a pixel value for a corresponding pixel in the output frame as a weighted pixel value corresponding to the determined minimal absolute value.
2. The method of claim 1 , wherein weight coefficients selected for the weighted pixel value depend on the distance between the frame and remaining frames in a frame pair.
3. The method of claim 1 , wherein the weight coefficients are determined using a parameter equal to a width of a bell-shaped function determining a weight coefficient for a frame number, and wherein the width determines extent of the noise reduction.
4. The method of claim 1 , wherein the number of frames in a video channel used for processing is a parameter for the noise reduction.
5. The method of claim 1 , wherein the number of frames in a video channel used for processing is twice a width of a bell-shaped curve.
6. The method of claim 1 , further comprising calculating an absolute value of a difference for a processed pixel and two pixels adjacent to the processed pixel in a row and selecting a resulting value from the three values using a median filter.