IMAGE ENCODING DEVICE, IMAGE DECODING DEVICE, IMAGE ENCODING METHOD, AND IMAGE DECODING METHOD

摘要

An image encoding device include a predicting unit for adaptively determining the size of each motion prediction unit block according to color component signals, and for dividing each motion prediction unit block into motion vector allocation regions to search for a motion vector, and a variable length encoding unit for, when a motion vector is allocated to the whole of each motion prediction unit block, performing encoding in mc_skip mode if the motion vector is equal to an estimated vector and a prediction error signal does not exist, and for, when each motion vector allocation region has a size equal to or larger than a predetermined size and a motion vector is allocated to the whole of each motion vector allocation region, performing encoding in sub_mc_skip mode if the motion vector is equal to an estimated vector and a prediction error signal does not exist.

主权项

1. An image decoding device which decodes a predictive-encoded bit stream to acquire a moving image signal, the bit stream being created by dividing each frame of the moving image signal into reference blocks each having a predetermined size and by performing a motion prediction for the reference blocks, the image decoding device comprising:
a decoder decoding the bit stream to acquire information indicating the size of each of the reference blocks, information indicating a threshold on a block size, a motion vector and a motion prediction mode for a motion prediction unit block corresponding to the reference block or block which is obtained by dividing the reference block hierarchically, the motion prediction mode specifying a shape of a region allocating the motion vector, the shape of region being obtained by dividing the motion prediction unit block, wherein the decoder decodes a first motion prediction mode for a first motion prediction unit block corresponding to the reference block, and determines whether or not the first motion prediction mode is a skip mode, and when the first motion prediction mode is not a skip mode and the size of the reference block is larger than the threshold, decodes a second motion prediction mode for a second motion prediction unit block which is obtained by dividing the reference block hierarchically, and determines whether or not the second motion prediction mode is a skip mode; a predictor, when the first motion prediction mode is a skip mode, determining an estimated vector from surrounding motion vectors, and setting the estimated vector as a motion vector for the first motion prediction unit block to create a prediction image, and when the first motion prediction mode is not a skip mode and the second motion prediction mode is a skip mode, determining an estimated vector from surrounding motion vectors, and setting the estimated vector as a motion vector for the second motion prediction unit block to create a prediction image, and when the first motion prediction mode is not a skip mode and the second motion prediction mode is not a skip mode, creating a prediction image based on the second motion prediction mode and the motion vector decoded by the decoder; and an adder, when the first motion prediction mode or the second motion prediction mode is a skip mode, adding a prediction error signal set to zero and the prediction image.