Patent ID: 8644388

Claim:
A method for approximating a DC coefficient of a first block of pixels of a first frame, comprising: calculating a luminance DC average value based on DC coefficients of first frame's macro-blocks without an approximation error; determining the DC coefficient of the first block based on the DC coefficient of a second block, wherein the second block is a part of a second frame, which is a reference frame of the first frame, the second block overlapping with a reference block of the first block and having the closest DC coefficient to the luminance DC average value; determining a third block belonging to a third frame that is a reference frame of the second frame, the third block having the largest overlap with a reference block of the second block; and determining the DC coefficient of the second block based on a DC coefficient of the third block; determining further DCT coefficients of the first block by calculating a DCT coefficient average value based on DCT coefficients of the first frame's macro-blocks without an approximation error; and determining the further DCT coefficients of the first block based on the DCT coefficient of a further second block, wherein the further second block is a part of the second frame, the further second block overlapping with the reference block of the first block and having the closest further DCT coefficient to the DCT coefficient average value, wherein when a current frame is a monochrome frame, the luminance DC average value is calculated based on the DC coefficients of a current frame intra-coded macro-block, making use of an absence any approximation error of intra-coded values, corresponding reference frames' forward, backward or bi-directionally predicted macro-blocks with zero motion vectors, making use of complete overlap of a reference region with the current sub block position and of the absence of the approximation error as motion vectors are zero, and corresponding reference frames' skipped macro-blocks for P-frames DC approximation, wherein in P-frames, skipped macro-blocks are equivalent to forward macro-blocks with zero motion vectors and no coded error.