US 5,489,944 A · Encoding method and apparatus to determine quantization levels using energy characteristics in the DCT domain

Abstract

An encoding method and apparatus uses energy characteristic of discrete cosine transform (DCT) domains for determination of a quantization level. The DCT domain is divided into for sub-domains. The energy characteristic of each macroblock is represented as one among the four domains such as simple, complicated, edge and plain domains. The buffer generates a first quantization level which is varied according to the buffer fullness in units of a slice. The energy characteristic information and the first quantization level of the buffer are used for determination of a second quantization level supplied to a quantizers. The quantizers quantize the transformation coefficient data according to the second quantization level generated in units of the macroblock. Thus, the viewer can feel less quantization error in sight. The encoding apparatus generates a second quantization level by only addition operation of the varied value of the first quantization level which is determined by the energy characteristic information to the first quantization level, thereby providing a quantization level generator capable of being implemented with simple hardware.

Claims14

Dependent claims

An encoding apparatus which quantizes and encodes image data to transmit the encoded data, said encoding apparatus comprising:

buffer means which receives the encoded data to transmit the received encoded data in a predetermined transfer rate, and generates a first quantization level which is varied so as to maintain the transfer rate invariably;
transformation means for transforming image data of an image domain into image data of a frequency domain in block units to thereby generate transformation coefficient data of the frequency domain;
image characteristic discrimination means for dividing a unit block frequency domain into a plurality of frequency sub-domains and generating energy characteristic information according to a ratio of the transformation coefficient data included in the respective frequency sub-domains;
quantization level determination means for receiving the energy characteristic information and the first quantization level and determining a second quantization level according to the energy characteristic information and the first quantization level to generate the determined second quantization level;
and
means for receiving the transformation coefficient data from the transformation means and quantizing the transformation coefficient data according to the second quantization level.

3 more elements

An encoding method which quantizes and encodes image data to transmit the encoded data through a buffer, the encoding method comprising the step of:

receiving the encoded data to generate a first quantization level which is varied in order to transmit the received data in a predetermined transfer rate;
transforming image data of an image domain into image data of a frequency domain in block units to thereby generate transformation coefficient data of the frequency domain;
dividing a unit block frequency domain into a plurality of frequency sub-domains;
generating energy characteristic information according to a ratio of the transformation coefficient data included in the respective frequency sub-domains;
determining a second quantization level according to the energy characteristic information and the first quantization level;
and
quantizing the transformation coefficient data according to the second quantization level.

4 more elements

Dependencies are inferred from the claim text.

Encoding method and apparatus to determine quantization levels using energy characteristics in the DCT domain

Life of this patent

Encoding method and apparatus to determine quantization levels using energy characteristics in the DCT domain

Life of this patent

Abstract

Claims14