A method of processing a digital image. The method comprises: populating (100) a bilateral grid (10) comprising a plurality of cells (20), based on information obtained from the image, each cell comprising at least one value; then cumulatively integrating (110) the at least one value over the bilateral grid to form an integrated grid comprising integrated values; generating (120) a modified bilateral grid, comprising computing the sum of the at least one value over a predetermined rectangular box of cells of the bilateral grid, by using the integrated values corresponding to the corners of the box; and slicing (130) the modified bilateral grid to generate an output image.