Cloud detection in all sky ConCam images by Gaussian fitting and valley detection in histogram

Clouds are the complex part to classify in the all sky Continuous Camera (ConCam) image due to their intensity similar to other objects and their diverse nature. The paper presents a histogram based technique to extract clouds in ConCam images. Small scale features are extracted by subtracting Gaussian fitted histogram from original histogram of an image. Valleys are then detected in these small scale features and based on these valleys, i.e. their intensity levels, different regions of sky are classified.

[1]  E. Pereira,et al.  The Use of Euclidean Geometric Distance on RGB Color Space for the Classification of Sky and Cloud Patterns , 2010 .

[2]  A Cazorla,et al.  Development of a sky imager for cloud cover assessment. , 2008, Journal of the Optical Society of America. A, Optics, image science, and vision.

[3]  Enio Bueno Pereira,et al.  A Simple Method for the Assessment of the Cloud Cover State in High-Latitude Regions by a Ground-Based Digital Camera , 2006 .

[4]  Jitendra Malik,et al.  Blobworld: Image Segmentation Using Expectation-Maximization and Its Application to Image Querying , 2002, IEEE Trans. Pattern Anal. Mach. Intell..

[5]  H.M. Wechsler,et al.  Digital image processing, 2nd ed. , 1981, Proceedings of the IEEE.

[6]  Paul Wintz,et al.  Digital image processing (2nd ed.) , 1987 .

[7]  S. K. Sengupta,et al.  Cloud field classification based upon high spatial resolution textural features: 1. Gray level co‐occurrence matrix approach , 1988 .

[8]  T. Bulik,et al.  All Sky Cameras for the characterization of the Cherenkov Telescope Array candidate sites , 2013, 1307.3880.

[9]  James Zijun Wang,et al.  Thin Cloud Detection of All-Sky Images Using Markov Random Fields , 2012, IEEE Geoscience and Remote Sensing Letters.

[10]  Xia Li,et al.  Cloud detection based on segmentation with statistical and geometry features , 2012, 2012 IEEE International Geoscience and Remote Sensing Symposium.

[11]  M. Hrabovsky,et al.  All Sky Camera instrument for night sky monitoring , 2014, 1402.4762.

[12]  Bülent Sankur,et al.  Survey over image thresholding techniques and quantitative performance evaluation , 2004, J. Electronic Imaging.

[13]  Josep Calbó,et al.  Retrieving Cloud Characteristics from Ground-Based Daytime Color All-Sky Images , 2006 .

[14]  Stan Z. Li,et al.  Markov Random Field Modeling in Image Analysis , 2001, Computer Science Workbench.

[15]  Ronald M. Welch,et al.  A neural network approach to cloud classification , 1990 .