Patent ID: 8059720

Claim:
A computer program product stored on a non-transitory, computer-readable medium comprising instructions for causing a processor to perform an image down-sampling transcoding method for converting a first image having a first format into a second image having a second format, the image down-sampling transcoding method comprising: (a) decoding a bit stream encoded in the first format; (b) down-sampling a macro block of a predetermined unit in the decoded first image by the use of a predetermined filtering method; (c) calculating rate-distortion costs corresponding to the down-sampled macro block of the first image by performing a predetermined calculation method for each of candidate block modes; and (d) performing an encoding process with the candidate block mode having the least rate-distortion cost, wherein the candidate block mode comprises one or more of a first candidate block mode and a second candidate block mode, the first candidate block mode comprises one or more of a plurality of intra block modes having the second format, and the second candidate block mode comprises one or more of a plurality of inter block modes and a skip mode having the second format, wherein the predetermined calculation method comprises a mean square error (MSE) method and a rate-distortion optimization (RDO) method and wherein the predetermined calculation method in (d) is performed as follows: when a candidate block mode is an intra block mode, determining the first candidate block mode by performing the MSE method for every detail mode comprised in every intra block mode in the second format to calculate an MSE cost and selecting a detail mode having the least MSE cost as the first candidate block mode, and then performing the RDO method on the first candidate block mode to calculate a rate-distortion cost of the first candidate block mode; and when the candidate block mode is not the intra block mode, performing the RDO method for every detail mode comprised in every inter block mode in the second format and a skip mode to calculate rate-distortion costs for every detail mode comprised in every inter block mode in the second format and the skip mode.