ADAPTIVE IMAGE COMPRESSION SYSTEM AND METHOD

• US 20140056516A1
• Filed: 03/14/2013
• Published: 02/27/2014
• Est. Priority Date: 08/22/2012
• Status: Active Grant

• Current Assignee: Mobai Company Limited, QURAM Co., Ltd.
• Original Assignee: FIngram Co., Ltd., QURAM Co., Ltd.
• Inventors: Wee, Young Cheul, Ahn, Young Hoon, Park, Sung Soo
• Granted Patent: US 8,948,530 B2
• Time in Patent Office: Days
• US Class Current: 382/166
• CPC Class Codes: G06T 9/00 Image coding bandwidth or redundancy reduction for static pictures H04N1/41; coding or decoding of static colour picture signals H04N1/64; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00
• CPC Class Codes: H04N 19/126 Details of normalisation or weighting functions, e.g. normalisation matrices or variable uniform quantisers
• CPC Class Codes: H04N 19/14 Coding unit complexity, e.g. amount of activity or edge presence estimation H04N19/146 takes precedence
• CPC Class Codes: H04N 19/154 Measured or subjectively estimated visual quality after decoding, e.g. measurement of distortion use of rate-distortion criteria H04N19/147
• CPC Class Codes: H04N 19/176 the region being a block, e.g. a macroblock
• CPC Class Codes: H04N 19/625 using discrete cosine transform [DCT]

Abstract

Provided are an adaptive image compression system and method. The adaptive image compression method includes a step of determining, at an adaptive image compression system, characteristics of an image that is to be compressed, a step of determining, at the adaptive image compression system, a quantization scale factor based on the characteristics of the image that is to be compressed, a step of generating an adaptive quantization table corresponding to the image that is to be compressed based on the determined quantization scale factor, and a step of encoding the image that is to be compressed using the generated adaptive quantization table.

Claims

1. An adaptive image compression method comprising:

determining, at an adaptive image compression system, characteristics of an image that is to be compressed;

determining, at the adaptive image compression system, a quantization scale factor based on the characteristics of the image that is to be compressed;

generating an adaptive quantization table corresponding to the image that is to be compressed based on the determined quantization scale factor; and

encoding the image that is to be compressed using the generated adaptive quantization table.

2. The adaptive image compression method of claim 1, wherein determining, at the adaptive image compression system, the characteristics of the image that is to be compressed comprises:

dividing a gray image corresponding to the image that is to be compressed into a plurality of blocks;

calculating a characteristic value of each of the divided blocks; and

determining the characteristics of the image that is to be compressed based on the calculated characteristic value of each of the divided blocks.

3. The adaptive image compression method of claim 2, wherein calculating the characteristic value of each of the divided blocks comprises

calculating, at the adaptive image compression system, an average value of each differential value of pixels that are included in one of the blocks, wherein the differential value is an average of differences between a pixel value of a predetermined pixel and pixel values of pixels surrounding the predetermined pixel.

4. The adaptive image compression method of claim 2, wherein determining the characteristics of the image that is to be compressed based on the calculated characteristic value of each of the divided blocks comprises:

classifying, at the adaptive image compression system, a characteristic of each of the blocks based on the characteristic value of each of the blocks; and

determining the characteristics of the image that is to be compressed based on the classified characteristic of each of the blocks.

5. The adaptive image compression method of claim 1, wherein determining, at the adaptive image compression system, the quantization scale factor based on the characteristics of the image that is to be compressed comprises determining, at the adaptive image compression system, a quantization scale factor value corresponding to the image that is to be compressed based on a quantization scale factor determination list that includes information about a corresponding quantization scale factor value according to the determined characteristics of the image that is to be compressed.

6. The adaptive image compression method of claim 1, wherein generating the adaptive quantization table corresponding to the image that is to be compressed based on the determined quantization scale factor comprises

generating, at the adaptive image compression system, a gray adaptive quantization table and a color adaptive quantization table based on the determined quantization scale factor and a reference quantization table.

7. A computer readable record medium which stores therein a program for carrying out an adaptive image compression method comprising:

determining, at an adaptive image compression system, characteristics of an image that is to be compressed;

determining, at the adaptive image compression system, a quantization scale factor based on the characteristics of the image that is to be compressed;

generating an adaptive quantization table corresponding to the image that is to be compressed based on the determined quantization scale factor; and

encoding the image that is to be compressed using the generated adaptive quantization table.

8. An adaptive image compressing system comprising:

a characteristic determination module which determines characteristics of an image that is to be compressed;

a quantization scale factor determination module which determines a quantization scale factor based on the determined characteristics of the image that is to be compressed;

an adaptive quantization table generation module which generates an adaptive quantization table corresponding to the image that is to be compressed based on the determined quantization scale factor; and

an encoder which encodes the image that is to be compressed using the generated adaptive quantization table.

9. The adaptive image compressing system of claim 8, wherein the characteristic determination module divides a gray image corresponding to the image that is to be compressed into a plurality of blocks, calculates a characteristic value of each of the divided blocks, and determines the characteristics of the image that is to be compressed based on the calculated characteristic value of each of the divided blocks.

10. The adaptive image compressing system of claim 9, wherein the characteristic determination module calculates an average value of each differential value of pixels included in one of the blocks as the characteristic value, wherein the differential value is an average of differences between a pixel value of a predetermined pixel and pixel values of pixels surrounding the predetermined pixel.

11. The adaptive image compressing system of claim 9, wherein the characteristic determination module classifies a characteristic of each of the blocks based on a classification reference of the characteristic value of each of the blocks, and determines the characteristics of the image that is to be compressed based on the classified characteristic of each of the blocks.

12. The adaptive image compressing system of claim 8, wherein the quantization scale factor determination module determines a quantization scale factor value corresponding to the image that is to be compressed based on a quantization scale factor determination list that includes information about a corresponding quantization scale factor value according to the determined characteristics of the image that is to be compressed.

13. The adaptive image compressing system of claim 8, wherein the adaptive quantization table generation module generates a gray adaptive quantization table and a color adaptive quantization table based on the determined quantization scale factor and a reference quantization table.