Image encoding and decoding apparatuses, image encoding and decoding methods, programs thereof, and recording media recorded with the programs

摘要

A method for encoding an image using an intraframe prediction is provided which includes selecting a gradient of a pixel value that is indicated by an image signal to be predicted among a plurality of gradient candidates, generating a predicted signal by applying a gradient in accordance with the distance from a prediction reference pixel based on the gradient, intraframe-encoding the image signal to be predicted based on the predicted signal, and encoding information indicating the size of the selected gradient. Alternatively, the method includes estimating the gradient of a pixel value that is indicated by an image signal to be predicted based on an image signal which has already been encoded, generating a predicted signal by applying a gradient in accordance with the distance from a prediction reference pixel based on the gradient, and intraframe-encoding the image signal to be predicted based on the predicted signal.

主权项

1. An image encoding apparatus for encoding an image using an intraframe prediction, comprising:
a processor programmed to select the optimum combination of a gradient of a pixel value that is indicated by an image signal to be predicted and a prediction mode from among combinations of a plurality of gradient candidates and prediction modes that are available to a block to be encoded to which pixels to be predicted belong, the combination of the gradient and the prediction mode being selected for each of the block sizes of the image signal including a 4×4 block size, the gradient candidates being defined as Δ×gradient[i] (0≦i