A new automatic exposure algorithm for video cameras using luminance histogram

Abstract

Automatic exposure (AE) is one of the indispensable functions of modern video cameras. According to the attention mechanism of human visual systems, peak regions in luminance histogram correspond to the region of no interest in an image. Based on this assumption, a new AE algorithm using the luminance histogram of an image is proposed in this paper. The algorithm finds the first two largest peak regions in the histogram and calculates the mean weighted luminance (MWL) of the entire image by weighting the luminance of pixels inside the two peak regions. The MWL is then used to control the exposure of video cameras. The weight of pixel luminance is decided by a set of quadratic curves, and the parameters of the quadratic curves are affected by the brightness of the image background. Fuzzy logic is also applied to optimize the practical AE systems. Results show that the proposed algorithm gives efficient exposure control over various scene tests.

Keywords

automatic exposure / luminance histogram / peak regions / weighting curves / fuzzy logic

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Acknowledgements

The authors would like to express their sincere thanks to Zhao Guangyao and Wei Xiaoxia, who have extended generous help to this development project. This work was supported by the National Natural Science Foundation of China (Grant No. 60772134), the 111 Project of China (Grant No. B08038), and the Special Fund for the United Laboratory of Xidian University and Huawei Technologies Co, Ltd on Multimedia Communication.

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2014 Higher Education Press and Springer-Verlag Berlin Heidelberg