Abstract: The MPEG4 is expanded to permit the use of the 4:2:2 format and the 4:4:4 format. To this end, there is provided an encoder adapted for encoding a picture in terms of a macro-block made up of a block of luminance Y and a block of chrominance Cr, Cb. The encoder includes a VOP encoding unit 3 for encoding the picture as reading of a flag (cbpc) specifying the state of encoding of the chrominance block and a flag (cbpcb, cbpcr) specifying the state of encoding of the chrominance block associated with the types of the chrominance Cb, Cr is adaptively changed responsive to a flag (chroma_type) representing the chrominance format of the picture and to the flag (cbpc) specifying the state of encoding of the chrominance block.

Abstract: The MPEG4 is expanded to permit the use of the 4:2:2 format and the 4:4:4 format. To this end, there is provided an encoder adapted for encoding a picture in terms of a macro-block made up of a block of luminance Y and a block of chrominance Cr, Cb. The encoder includes a VOP encoding unit 3 for encoding the picture as reading of a flag (cbpc) specifying the state of encoding of the chrominance block and a flag (cbpcb, cbpcr) specifying the state of encoding of the chrominance block associated with the types of the chrominance Cb, Cr is adaptively changed responsive to a flag (chroma_type) representing the chrominance format of the picture and to the flag (cbpc) specifying the state of encoding of the chrominance block.

Abstract: A picture encoding apparatus, a picture encoding method, a picture decoding method and a presentation medium capable of making efficient random accesses at a high speed.

Abstract: An image-coding format converting apparatus comprising an EMPEG2 image decoder 30, a resolution/frame rate converter 31, a motion vector converter 32, and an MPEG4 encoder 33. The EMPEG2 decoder 30 decodes a bit stream of EMPEG2 image codes, generating an image signal. The resolution/frame rate converter 31 converts the image signal. The MPEG4 encoder 33 encodes the output of the resolution/frame rate converter 31, generating a bit stream of MPEG4 image codes. In the resolution/frame rate converter 31, pixels are added or extracted in accordance with the start position of a macro block, thus adjusting the input image signal to one than can easily be encoded to MPEG4 image codes. The motion vector converter 32 generates an MPEG4 motion vector from parameters such as an MPEG2 motion vector. The MPEG4 encoder 33 uses the MPEG4 motion vector to encode the output of the resolution/frame rate converter 31.

Abstract: Desired shape information is selected from a shape information template that holds the shape information corresponding to a plurality of shape information images, and in an encoder, the MPEG4 image encoding bit stream is generated, using the selected shape information and the texture image (original image, etc.) data.