Bilateral alpha omega: calculating LUT argument with few arithmetic operations

摘要

According to a first aspect, a method is provided. The method includes obtaining an M×N array of pixel values an image; determining a weight selection value for position x,y in the M×N array; and using the weight selection value to obtain a weight value for use in a filter for filtering the image. Determining the weight selection value for position x,y (omegax,y) includes: a) retrieving a previously determined weight selection value for position x,y−1 (omegax,y−1); b) retrieving a previously determined alpha value (a) for position x,y−1; c) calculating a delta value (d); and d) calculating omegax,y=omegax,y−1−a+d. Calculating d includes: i) retrieving a first previously determined value (omega_row); i) retrieving a second previously determined value (alpha_row); and ii) calculating d=omega_row−alpha_row+abs(Ax+1,y+1−Ax+1,y+2), wherein Ax+1,y+1 is the value stored in position x+1,y+1 of the array and Ax+1,y+2 is the value stored in position x+1,y+2 of the array.