1. Overview

Currently most image and video coding systems and standards such as MPEG-1/2 and H264/AVC use transform-based techniques followed by quantization and entropy coding for performing compression. The key idea is that transforms de-correlate the signal and compact the energy of a block into few low pass coefficients, which after quantization and de-quantization could still represent the signal rather accurately. Nevertheless, this quantization/de-quantization process needs to be carefully designed in order to have the best possible subjective and objective quality.

In the encoder of H.264/AVC reference software, the scalar dead-zone quantization is adopted. In order to improve further the performance, other two adaptive quantization techniques are also introduced, which are both based on how to adjust the size of dead-zone and control the rounding behavior. In this tutorial, we will first introduce the principle of H.264/AVC normal quantization scheme, then discuss the adaptive rounding method which select adaptively rounding offset using an equal expected-value property. Finally, a more complex rate-distortion optimized quantization will be discussed.

本文来自: JM KTA Tutorial: Quantization Techniques – Part 1