A Hybrid Thresholding Algorithm for Cloud Detection on Ground-Based Color Images

Journal of Atmospheric and Oceanic Technology - Tập 28 Số 10 - Trang 1286-1296 - 2011
Qingyong Li1, Weitao Lu2, Jun Yang2
1School of Computer and Information Technology, Beijing Jiaotong University, Beijing, China
2Institute of Atmospheric Sounding, Chinese Academy of Meteorological Sciences, Beijing, China

Tóm tắt

Abstract Cloud detection is the precondition for deriving other information (e.g., cloud cover) in ground-based sky imager applications. This paper puts forward an effective cloud detection approach, the Hybrid Thresholding Algorithm (HYTA) that fully exploits the benefits of the combination of fixed and adaptive thresholding methods. First, HYTA transforms an input color cloud image into a normalized blue/red channel ratio image that can keep a distinct contrast, even with noise and outliers. Then, HYTA identifies the ratio image as either unimodal or bimodal according to its standard deviation, and the unimodal and bimodal images are handled by fixed and minimum cross entropy (MCE) thresholding algorithms, respectively. The experimental results demonstrate that HYTA shows an accuracy of 88.53%, which is far higher than those of either fixed or MCE thresholding alone. Moreover, HYTA is also verified to outperform other state-of-the-art cloud detection approaches.

Từ khóa


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Journal of Atmospheric and Oceanic Technology

Tập 28 Số 10

1286-1296

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