Patent ID: 7437009

Claim:
An image coding method performed by an apparatus comprising: a still frame judgment step of judging whether or not a target frame to be coded is a still frame; a still frame coding judgment step of judging whether a frame after the target frame is to be subjected to still frame coding or normal frame coding, the still frame coding having a higher image quality than the normal frame coding, on the basis of coding information of the target frame that is determined in coding a frame previous to the target frame; a quantization parameter value control step of controlling a quantization scale of an externally inputted quantization parameter, on the basis of an output from the still frame judgment step; a skip macroblock judgment step of judging whether each macroblock in the target frame is a skip macroblock or not, by using the quantization parameter controlled in the quantization parameter value control step, and a difference value between the target frame and a reference frame; and a coding step of determining a coding method of the frame after the target frame on the basis of the judgment by the still frame coding judgment step, and coding the target frame on the basis of the coding information that is determined in coding the previous frame, wherein the coding step includes a high image quality coding step of subjecting any macroblock among a plurality of macroblocks located at a same position in a plurality of continuous frames which are judged as still frames in the still frame judgment step, to at least one-time still frame coding having a higher image quality relative to coding for other macroblocks.