Patent ID: 8542740

Claim:
An image coding apparatus which converts first coded data coded in a first coding scheme into second coded data coded in a second coding scheme, said image coding apparatus comprising: a decoding unit configured to decode the first coded data to generate a decoded picture and to generate decoding information containing motion vectors; a coding unit configured to code, in the second coding scheme, the decoded picture generated by said decoding unit, so as to generate the second coded data including a coded picture and coding information containing motion vectors; a decoding information holding unit configured to hold the decoding information generated by said decoding unit; a coding information holding unit configured to hold the coding information generated by said coding unit; and a basic motion information generating unit configured to (i) generate basic motion information to be used by said coding unit to estimate the motion vectors contained in the coding information, the basic motion information being generated using motion information obtained from the decoding information generated by said decoding unit when generating a currently decoded picture, when a picture type to be used by said coding unit to re-code the currently decoded picture is a P picture, and (ii) generate the basic motion information using motion information obtained from the coding information generated by said coding unit when generating the second coded picture using a previously decoded picture previously decoded by said decoding unit and that has already been re-coded by said coding unit, when the picture type to be used by said coding unit to re-code the currently decoded picture is a B picture, wherein said coding unit is configured to (i) determine a search range according to the basic motion information generated by said basic motion information generating unit, (ii) estimate the motion vectors of the currently decoded picture in the determined search range, and (iii) generate the second coded data including the coded picture and the coding information containing the estimated motion vectors.