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2024 Vol.12, Issue 2 Preview Page

Research Article

30 June 2024. pp. 71-83
Abstract
손상된 디지털 이미지를 복원하는 통계적 방법으로 EM 알고리즘이 있다. 유연한 확률적 모델을 적용할 수 있어 오염이 심한 화상을 복원하는데 유효성이 있지만, 화소 단위로 화상을 복원하기 때문에 알고리즘의 수렴속도가 문제가 있다. 이것을 개선한 것으로 OSL 알고리즘이 있는데, 이 알고리즘은 수렴속도 개선과 함께 초월함수 형태의 복잡한 패널티가 주어져도 로그우도에 수렴하는 장점이 있다. 그러나 이 알고리즘은 평활상수 𝜆가 특정한 영역에서만 수렴하는 제한이 있다. 이러한 문제를 해결하기 위해 저자는 MPEMG 알고리즘을 제안한 바가 있다. 그러나 이것은 평활상수 𝜆가(0<𝜆<∞) 의 영역에서 전역적으로 수렴하는 장점을 갖지만, 페널티 로그 우도를 증가시키는 수렴속도가 통계적 방법의 복원알고리즘이 가지는 한계를 극복하지 못했다. 이러한 문제점을 극복하기 위해서 PS-PEMG 알고리즘을 제안한다. 제안한 알고리즘의 기본 구조는 반복마다 모수들을 동시에 갱신하지 않고 몇 개의 픽셀로 이루어진 그룹들을 순차적으로 갱신하는 방법이다. 따라서 제안한 알고리즘의 수렴 속도가 MPEMG 알고리즘보다 빠르다는 것을 화상 모의실험을 통하여 밝힌다.
The EM algorithm is a statistical method for restoring damaged digital images, utilizing a flexible probabilistic model that can effectively restore highly contaminated images. However, because it restores images pixel by pixel, the convergence speed of the algorithm poses a challenge. The OSL algorithm improves upon this by enhancing the convergence speed and converging to the log-likelihood even with complex transcendental function forms of penalties, but it has limitations as it converges only within specific smoothing constant regions. To address this, the MPEMG algorithm was proposed, which converges globally in the region of the smoothing constants, but it has not overcome the limits of statistical restoration algorithms in terms of increasing the penalty log-likelihood convergence speed. To overcome these issues, the PS-PEMG algorithm is proposed. The core structure of the proposed algorithm does not update the parameters simultaneously at each iteration, but rather updates groups of pixels sequentially. Therefore, the convergence speed of the proposed PS-PEMG algorithm is faster than that of the MPEMG algorithm, as demonstrated through image simulation experiments.
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Information
  • Publisher :The Society of Convergence Knowledge
  • Publisher(Ko) :융복합지식학회
  • Journal Title :The Society of Convergence Knowledge Transactions
  • Journal Title(Ko) :융복합지식학회논문지
  • Volume : 12
  • No :2
  • Pages :71-83