Rapid intra-frame mode decision method specific to high efficiency video coding standard

The invention discloses a rapid intra-frame mode decision method specific to a high efficiency video coding standard. The method comprises the following steps: (1) selecting a prediction unit (PU) being N*N in size; (2) calculating an average gradient value of pixel points in the PU with a Sobel operator; (3) determining a threshold value for judging an intra-frame prediction mode; (4) initially judging the intra-frame prediction mode according to the average gradient value of the pixel points in the PU and the threshold value for judging the intra-frame prediction mode; (5) calculating gradient directions of the pixel points in the PU according to a gradient value of each pixel point in the PU calculated by the Sobel operator; and (6) performing table lookup according to the gradient directions of the pixel points of the PU in order to determine the intra-frame prediction mode. In the rapid intra-frame mode decision method, a Sobel edge detection operator is adopted, so that the intra-frame decision speed is increased under the situation that the decision accuracy of a direction mode is kept constant; the complexity is low; the calculation amount is small; only a small amount of code rate is increased; and a large amount of coding time is saved.