Patent ID: 9729878
Date: 2017-08-08
CPC Classifications: H04N

Claim:
1. An image encoding method comprising: generating a first bitstream by encoding an input image, and generating a first decoded image by encoding and decoding the input image; and generating a second bitstream by encoding the input image using the first decoded image, and generating a second decoded image by encoding and decoding the input image; wherein the second decoded image has resolution or image quality higher than resolution or image quality of the first decoded image, the generating of a second bitstream and a second decoded image includes generating a prediction block for a current block by intra prediction, in the generating of a prediction block, the prediction block is generated using (i) pixels included in the second decoded image as top and left reference pixels for the current block, and (ii) pixels included in the first decoded image as right and bottom reference pixels for the current block, the intra prediction includes a first mode in which a prediction pixel for a current pixel is generated using reference pixels in an upper direction, a left direction, a lower direction, and a right direction of the current pixel included in the current block, and in the generating of a prediction block, in the first mode, the prediction pixel is generated using (i) pixels that are in an upper direction and a left direction of the current block and are included in the second decoded image, as reference pixels in an upper direction and a left direction of the current block, and (ii) pixels that are in a right direction and a lower direction of a co-located block of the current pixel and are included in the first decoded image, as reference pixels in a right direction and a lower direction of the current pixel.