Extract

The use of digital cameras to capture sky images for measuring sky brightness is an inexpensive and accurate method. However, a digital image has numerous pixels each containing colour data that is impossible to calculate into luminance values manually. Therefore, in this paper we describe the algorithm of a computer program that can automate the calculation process and simultaneously compare the measured sky luminance with ISO/CIE Standard Sky luminance, using diffuse horizontal illuminance, to determine the occurrence frequency.

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