Image coder and image coding method, and image decoder and image decoding method, and quantization control method and inverse quantization control method, and data recording medium

摘要

An image coding apparatus 1 of the present invention comprises a coding controller 112a for generating a transparency coding parameter 121 for controlling coding process for transparency signals on the basis of a pixel value coding parameter 104 for controlling coding process for pixel value signals and performs coding process for transparency signals 102 on the basis of the transparency coding parameter 121.The image coding apparatus 1 above constructed can control an image quality obtained from transparency signals of each image included in a composite image according to an image quality of pixel value signals of each image of the composite image, and thus it is possible to reduce redundant information of coded transparency signals 106 resulting from coding the transparency signals without degrading an image quality of each image, thereby implementing recording and transmission of image signals with fewer bits with no degradation of image quality.