Apparatus for decoding chroma image using luma quantization

摘要

Provided is a method that derives a chroma intra prediction mode of a prediction unit, determines a size of a current chroma block using luma transform size information, generates a chroma prediction block of the current chroma block using the chroma intra prediction mode, generates a chroma residual block of the current chroma block using the chroma intra prediction mode and a chroma quantization parameter, generates a chroma reconstructed block adding the chroma prediction block and the chroma residual block, and the chroma quantization parameter is generated using a luma quantization parameter and information indicating the relationship between the luma quantization parameter and the chroma quantization parameter. Therefore, the coding efficiency is improved by adjusting the chroma quantization parameter per picture. Also, the amount of bits for transmitting the luma and chroma quantization parameters is reduced by encoding the luma quantization parameter using neighboring luma quantization parameters.

主权项

1. An apparatus for decoding a chroma image, comprising:
an intra prediction unit for deriving a chroma intra prediction mode of a prediction unit, determining a size of a chroma prediction block using luma transform size information and generating the chroma prediction block using the chroma intra prediction mode; a residual block generating unit for generating a chroma residual block using the chroma intra prediction mode and a chroma quantization parameter; and an adder for generating a chroma reconstructed block by adding the chroma prediction block and the chroma residual block, wherein the chroma quantization parameter is generated using a luma quantization parameter which is generated per quantization unit and information indicating the relationship between the luma quantization parameter and the chroma quantization parameter, the luma quantization parameter is generated using a luma quantization parameter predictor and a luma differential quantization parameter, and the luma quantization parameter predictor is generated using two quantization parameters which are determined in a predetermined order among a left luma quantization parameter, an above luma quantization parameter and a previous luma quantization parameter.