Patent ID: 8542751

Claim:
A computer-implemented method comprising: identifying locations of potential blocking artifacts in an image without prior identification of coding parameters of a compressed version of the image, the image comprising multiple pixels, wherein the identifying locations of potential blocking artifacts comprises: determining a horizontal gradient for a selected pixel in the image; determining whether the horizontal gradient for the selected pixel differs from horizontal gradients of other pixels in the same row as that of the selected pixel in a manner that indicates a sudden change in pixel intensity; determining whether a length exceeds a threshold length, wherein the length is of adjacent pixels in the same column as that of the selected pixel and each of the adjacent pixels has a horizontal gradient that indicates a sudden change in pixel intensity relative to horizontal gradients of other pixels in its same row; and identifying the adjacent pixels as potentially having blocking artifacts in response to the length exceeding the threshold length; determining strength of blocking artifacts in the image; and applying filtering to the image based in part on the identified locations and the determined strength, wherein parameters used in applied filtering are selected based in part on the determined strength.