Patent ID: 8488889

Claim:
An image decoder that decodes a color image signal in 4:4:4 format based on an input of a bit stream generated by compression-encoding a color image which is formed of a plurality of color components in 4:4:4 format, the color image being compression-encoded in units of regions obtained by dividing the color image into predetermined regions, the image decoder comprising: a header analyzing unit that extracts common encoding/independent encoding identification information from the bit stream; a decoding unit that decodes, for each of the regions, an inter-prediction mode, a motion vector, and a reference image identification number included in the bit stream, and decodes a prediction error signal of each of the regions; a predicted-image generating unit that generates a predicted image on the basis of the inter-prediction mode, the motion vector, and the reference image number which have been decoded; and an adding unit that generates a decoded image by adding the decoded prediction error signal and the predicted image, wherein the decoding unit decodes the same inter-prediction mode, the same motion vector, and the same reference image identification number which are commonly used for all the color components, in a case where the common encoding/independent encoding identification information indicates that the regions serving as the units of encoding are encoded by a same inter-prediction mode for respective color components, and decodes a separate inter-prediction mode, a separate motion vector, and a separate reference image identification number in units of the regions for respective color components, in a case where the common encoding/independent encoding identification information indicates that the regions serving as the units of encoding are respectively encoded by a separate inter-prediction mode for respective color components, and the predicted-image generating unit generates a predicted image by using the inter-prediction mode, the motion vector, and the reference image identification number which have been decoded, for respective color components.