정보처리학회논문지C (The KIPS Transactions:PartC)

한국정보처리학회 (Korea Information Processing Society)
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실시간 처리를 위한 쿼드트리 기반 무손실 영상압축 및 암호화

QuadTree-Based Lossless Image Compression and Encryption for Real-Time Processing

  • 윤정오 (경운대학교 정보통신공학과) ;
  • 성우석 (경북대학교 대학원 전자공학과) ;
  • 황찬식 (경북대학교 전기전자공학부)
  • Yoon, Jeong-Oh (Kyungwoon University) ;
  • Sung, Woo-Seok (Dept.of Electronics Engineering, Graduate School of Kyungpook National University) ;
  • Hwang, Chan-Sik (Dept.of Electronics Electrical Engineering, Kyungpook National University)
  • 발행 : 2001.10.01
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⟨ 이전 논문 다음 논문 ⟩

초록

일반적으로 무손실 영상압축 및 암호화 방법에는 압축과 암호화 과정이 독립적으로 이루어진다. 압축 후 암호화를 수행하면 압축열이 암호에 대한 평문으로 사용되므로 압축에 따른 엔트로피가 감소하여 랜덤한 성질을 갖게된다. 그러나 압축열 전체에 대한 암호화는 수행시간이 길어져 실시간 처리를 저해하는 원인이 되기도 한다. 본 논문에서는 무손실 영상압축과 암호의 결합에서 전체 처리시간을 줄이는 방법을 제안한다. 이는 쿼드트리 압축 알고리즘으로 그레이 영상을 분해하여 구조부분만을 암호화하는 방법이다. 아울러 영상의 무상관성과 동질영역을 확보하기 위한 변환과정을 수행하여 무손실 압축성능을 개선하였고, 쿼드트리 분해시 암호화되지 않은 데이터를 레벨별로 재구성하여 안전성을 갖도록 하였다. 모의 실험을 통하여 제안한 방법이 영상 압축율의 개선과 암호화 방법의 안전성 확보 및 실시간 처리가 가능함을 확인하였다.

Generally, compression and encryption procedures are performed independently in lossless image compression and encryption. When compression is followed by encryption, the compressed-stream should have the property of randomness because its entropy is decreased during the compression. However, when full data is compressed using image compression methods and then encrypted by encryption algorithms, real-time processing is unrealistic due to the time delay involved. In this paper, we propose to combine compression and encryption to reduce the overall processing time. It is method decomposing gray-scale image by means of quadtree compression algorithms and encrypting the structural part. Moreover, the lossless compression ratio can be increased using a transform that provides an decorrelated image and homogeneous region, and the encryption security can be improved using a reconstruction of the unencrypted quadtree data at each level. We confirmed the increased compression ratio, improved encryption security, and real-time processing by using computer simulations.

키워드

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