Patent ID: 8204105

Claim:
A transcoder comprising: decoder means for decoding a first coded image; means for calculating a macroblock evaluation value indicating the degree of dispersion in pixel values inside a macroblock of an image obtained by decoding in said decoder means; means for obtaining an average macroblock evaluation value by averaging said macroblock evaluation values in a frame; and encoder means for encoding the image obtained by decoding in said decoder means to generate a second coded image, wherein said encoder means comprises means for acquiring an average quantization step value by averaging quantization step values in a frame of said first coded image; weighting value calculation means for calculating a weighting value for each macroblock on the basis of the difference between said macroblock evaluation value and said average macroblock evaluation value; and step value calculation means for calculating a converting quantization step value for each macroblock of said second coded image on the basis of a value obtained by adding said weighting value to said average quantization step value.