Journal of the Institute of Electronics Engineers of Korea SP (대한전자공학회논문지SP)

The Institute of Electronics and Information Engineers (대한전자공학회)
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DCT-Based Energy-Ratio Measure for Autofocus in Digital Camera

이산 코사인 변환 계수의 에너지 비를 사용한 디지털 카메라용 초점 간 연산자

  • Lee, Sang-Yong (Department of Electronics Engineering, Korea University)
  • 이상용 (고려대학교 전자공학과)
  • Published : 2008.11.25
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Abstract

A DCT-based energy-ratio measure for autofocus in digital camera is proposed in this paper. This measure, namely AC2DC1 and AC5DC1, determines the sharpness of an image using a ratio between AC and DC energy in the DCT domain. This method is derived from energy analysis of DCT coefficients. Autofocus score calculation method is used to assess the performance of the proposed measure and to compare it with other measures. Experimental results under various conditions verify the robustness of the proposed focus measure for the Gaussian as well as impulsive noises.

본 논문에서는 이산 코사인 변환 계수의 에너지 비를 사용한 디지털 카메라용 초점 값 연산자를 제안하였다. 제안된 AC2DC1 및 AC5DC1 초점 값 연산자는 이산 코사인 변환 계수의 AC와 DC 계수의 에너지 비를 사용하여 이미지의 선명한 정도를 판단하는데, 이는 여러가지 표본 영상들의 이산 코사인 변환 에너지 분석에 바탕을 두고 있다. 또한 제안된 연산자와 기존의 여섯 가지 연산자를 비교하기 위해 초점 값의 선형성과 기울기를 종합적으로 측정할 수 있는 점수 계산 방법을 도입했으며, 이를 통해 잡음이 없는 상태, 임펄시브 및 가우시안 잡음이 있는 세 가지 상황 하에서 제안된 연산자의 성능을 검증하였다.

Keywords

References

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