Patent ID: 6961471

Claim:
A picture encoding apparatus comprising: a resolution conversion unit configured to reduce an alpha-map signal according to a conversion ratio of 1, 1/2, or 1/4, the alpha-map signal being a signal for discriminating a picture between an object region and a background region, and configured to output a reduced alpha-map signal; an encoder configured to encode the reduced alpha-map signal and a video signal and configured to output a coded signal including a coded alpha-map signal and a coded picture signal; and a multiplexer configured to multiplex the coded signal and a reduction ratio setting information signal indicating the conversion ratio, and configured to output a bit stream representing a multiplexed signal including the coded signal and the reduction ratio setting information; and an enlargement resolution conversion unit configured to receive the reduced alpha-map signal output by the resolution conversion unit, and configured to output an enlarged alpha-map signal obtained by enlarging the reduced alpha-map signal by an amount which inversely corresponds to the reduction ratio setting information signal output by the conversion ratio of 1, 1/2, or 1/4.