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DCT-Based Energy-Ratio Measure for Autofocus in Digital Camera  

Lee, Sang-Yong (Department of Electronics Engineering, Korea University)
Publication Information
Journal of the Institute of Electronics Engineers of Korea SP / v.45, no.6, 2008 , pp. 88-94 More about this Journal
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.
Keywords
Digital Camera; Autofocus; Focus measure; Impulsive noise; Gaussian noise;
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