Improved image coding system having functions for controlling generated amount of coded bit stream

TL;DR: A quantizer employed in the video signal encoding system comprises a quantization parameter deciding block, a quantizer control block, and a quantifier which classifies transform coefficients included in each block into high frequency coefficients and low frequency coefficients based on the quantization mode signal as mentioned in this paper.

Abstract: A video signal encoding system, for encoding a video signal to provide an encoded signal, includes a transform coder for encoding the video signal on a block-by-block basis to generate blocks of transform coefficients, wherein the video signal includes a multiplicity of frames, each frame having blocks of pixels. A quantizer employed in the video signal encoding system comprises a quantization parameter deciding block; a quantizer control block for deciding a quantization mode signal which represents an activity of the video signal; and a quantizer which classifies transform coefficients included in each block into high frequency coefficients and low frequency coefficients based on the quantization mode signal, modifies the high frequency coefficients, to thereby provide blocks of modified transform coefficient, and quantizes the blocks of modified transform coefficients by using the quantization parameter.