Patent ID: 9706209
Date: 2017-07-11
CPC Classifications: G06T,H04N

Claim:
1. A system for adaptively compensating distortion caused by video compression, comprising: an edge detector ( 201 ), a flat/texture detector ( 202 ), a ringing artifact area locator ( 203 ), a line detector ( 204 ), a block boundary detector ( 205 ), a blocking artifact filtering area locator ( 206 ), a blocking artifact suppressing enable judge ( 207 ), an adaptive mean filter ( 208 ), a filtering selector ( 209 ) and an output fusion ( 210 ); wherein input ends of the edge detector ( an output end of the filtering selector ( wherein the edge detector ( in the equations, edge_tmp(i,j) and stedge_tmp(i,j) are the whole edge information and the strong edge information of a pixel at location (i,j) of an image respectively; and the threshold values SOBEL_HIGH_TH and SOBEL_LOW_TH are 270 and 65, respectively; the edge detector ( in the equations, edge_corrosion(i,j) is the whole edge information of a pixel at location of (i,j) of an image after erosion, and edge_expansion(i, j) is the whole edge information of the pixel at location of (i, j) of the image after dilation, and edge_map(i,j) is relatively accurate whole edge information of the pixel at location of (i,j) of the image output by the edge detector the edge detector the flat/textural detector ( compare the calculated brightness change value with defined threshold values TEXTURE_HIGH_TH, 2·TEXTURE_LOW_TH and TEXTURE_LOW_TH: in the equation, texture_map(i, j) represents a textural degree of a pixel at location of (i,j) of an image, the smaller the value represents that the pixel to be processed is located in even flatter area; the threshold values TEXTURE_HIGH_TH and TEXTURE_LOW_TH take values of 16 and 2; the ringing artifact area locator ( in the equation, ring_map(i, j) represents the ringing artifact condition of a pixel at location of (i, j) of an image: if ring_map(i, j) is equal to 3, it represents that the pixel to be processed is located at the edge or a textural area, which is required to be retained instead of being filtered; if ring_map(i, j) is equal to 2, it represents that the pixel to be processed is close to a strong edge, since the ringing artifact is more serious when close to the strong edge, thus a stronger filtering method is required to suppress the ringing artifact; if ring_map(i, j) is equal to 1, it represents that a pixel to be processed is close to a weak edge, a weaker filtering method is required to suppress the ringing artifact; and if ring_map(i, j) is equal to 0, it represents that a pixel to be processed is not a pixel having ringing artifact, the suppression of ringing artifact is not required; the method of detecting single-pixel line by the line detector a method of detecting block boundary by the block boundary detector ( in the equations, D in a 7×6 window, according to the continuity of the block boundary in a vertical direction, only if at least four continuous rows satisfy the three conditions of equation (11) and satisfy that P a 6×7 window is taken as the candidate pixel matrix, and conduct a method for detecting a horizontal block boundary, which is similar to the method for detecting a vertical block boundary, and finally obtains a detection result of hbd_map(i, j) of a horizontal block boundary; in combination with the vertical and horizontal boundary information, finally whole block boundary information bd_map(i, j) and strong block boundary information stbd_map(i, j) is obtained as the output of block boundary detector the blocking artifact filtering area locator ( the blocking artifact suppressing filtering enable judge ( in the equation, TH_BLK_RATIO1 and TH_BLK_RATIO2 take values of 1/64 and 23/512; if deblk_glen adaptive mean filter ( in the equations, y(i, j) is the brightness of the present pixel to be processed; y′(i, j) is a brightness filtering result using a M×N window with y(i, j) as the central pixel during filtering; y(i+s, j+t) is a brightness value of a pixel at the location of (i+s, j+t) within a M×N window, ω(i+s, j+t) is a weight corresponding to the pixel y(i+s, j+t): and filter_th is an adaptive filtering threshold value obtained from equation (19): in the equation, α the adaptive filter ( the filtering selector ( the output fusion ( in the equation, y in the equation, ω′(i+s, j+t) represents brightness differences between a central pixel and other pixels within a 5×5 window with pixel (i, j) being a central pixel, and the threshold value BLEND_TH is defined to be 3.