Efficiency Analysis of the Autofocusing Algorithm Based on Orthogonal Transforms

Przemysław Śliwiński, Krzysztof Berezowski, Piotr Patronik, Paweł Wachel

Institute of Computer Engineering, Control and Robotics, Wroc?aw University of Technology, Wroc?aw, Poland.

DOI: 10.4236/jcc.2013.16008                

Abstract

Efficiency of the autofocusing algorithm implementations based on various orthogonal transforms is examined. The algorithm uses the variance of an image acquired by a sensor as a focus function. To compute the estimate of the variance we exploit the equivalence between that estimate and the image orthogonal expansion. Energy consumption of three implementations exploiting either of the following fast orthogonal transforms: the discrete cosine, the Walsh-Hadamard, and the Haar wavelet one, is evaluated and compared. Furthermore, it is conjectured that the computation precision can considerably be reduced if the image is heavily corrupted by the noise, and a simple problem of optimal word bit-length selection with respect to the signal variance is analyzed.

Keywords

Auto-Focusing; Image Variance; Discrete Orthogonal Transforms; Word-Length Selection; Architectural Performance Evaluation

Conflicts of Interest

The authors declare no conflicts of interest.

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