Patent ID: 7079582

Claim:
An image coding apparatus comprising: a coder that performs image coding processing for an image on a per macroblock basis; a macroblock counter that counts the number of macroblocks that are image coding processed in the coder for a transmission unit; a bit counter that, with respect to the transmission unit that is generated using a plurality of macroblocks coded in the coder, counts the amount of codes included in the transmission unit; a significance decider that determines an average amount of codes per macroblock in the transmission unit, from the counted number of macroblocks in the transmission unit and the counted amount of codes in the transmission unit, and determines an image decoding significance of the transmission unit, as it would be perceived at a destination of the transmission unit, according to the determined average amount of codes per macroblock; and a significance assigner that assigns significance information representing the determined image decoding significance to the transmission unit for inclusion therein, wherein: the significance decider comprises: an average code amount calculator that divides the counted amount of codes included in the transmission unit by the counted number of macroblocks in the transmission unit to determine the average amount of codes per macroblock in the transmission unit; a threshold calculator that calculates a threshold from a frame rate and a bit rate of the transmission unit; and a threshold comparator that outputs, when the determined average amount of codes per macroblock exceeds the calculated threshold, the significance information for use by the significance assigner and in determining whether to store the transmission unit for a prospective retransmission.