Journal of the Korea Computer Graphics Society (한국컴퓨터그래픽스학회논문지)

Korea Computer Graphics Society (한국컴퓨터그래픽스학회)
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On Improving Compression Ratio of JPEG Using AC-Coefficient Separation

교류 계수 분할 압축에 의한 JPEG 정지영상 압축 효율 향상 기법 연구

  • 안영훈 (아주대학교 컴퓨터공학과) ;
  • 신현준 (아주대학교 미디어학부) ;
  • 위영철 (아주대학교 정보및컴퓨터공학부)
  • Received : 2009.11.25
  • Accepted : 2010.01.11
  • Published : 2010.03.01
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Abstract

In this paper, we introduce a novel entropy coding method to improve the JPEG image compression standard. JPEG is one of the most widely used image compression methods due to its high visual quality for the compression ratio, and especially because of its high efficiency. Based on the observation that the blocks of data fed to the entropy coder usually contain consecutive sequences of numbers with small magnitudes including 0, 1, and -1, we separate those sequences from the data and encode them using a method dedicated to those values. We further improve the compression ratio based on the fact that this separation makes the lengths of blocks much shorter. In our experiment, we show that the proposed method can outperform the JPEG standard preserving its visual characteristics.

본 논문에서는 JPEG 표준의 엔트로피 부호화 과정을 개선하여 압축률을 향상시키기 위한 방법을 제안한다. JPEG은 비교적 높은 화질 대비 압축률을 가지며, 특히 부호화와 복호화가 매우 효율적이어서 많은 응용에 사용된다. 본 논문에서는 JPEG의 이산 코사인 변환과 양자화, 재정렬 등의 과정을 거친 정보에 0, -1, 1등의 작은 값들이 연속적으로 나타난다는 관찰 결과에 착안하여 이들을 분리하고 JPEG의 방식 보다 효율적인 방법으로 엔트로피 부호화 함으로써 압축률을 향상시키는 방법을 제안한다. 이와 같은 방법을 통하여 다양한 화질의 영상에서 JPEG보다 높은 압축률을 얻을 수 있음을 실험적으로 확인하였다.

Keywords

References

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