A scorch extraction method for the Campbell-Stokes sunshine recorder based on multivariable thresholding

The Campbell-Stokes sunshine recorder is an instrument which can measure the solar radiation by using the scorch on the recorder card. It is short for C-S. The weak scorch and the strong scorch represent different solar radiation. The weak scorch is so hard to extract that the radiation represented by the weak scorch always be neglected. The present methods reduce the accuracy of extraction, because these methods only extract the strong scorch and falsely treat the weak scorch as background. The RGB (red, green, blue) color image has more details of scorch than gray image, so a new method for scorch extraction based on the multivariable thresholding is proposed in this paper. The method segments the scorch with self-adaptive thresholds and optimizes the extraction with the amendatory coefficient, consequently, the robustness and accuracy of the algorithm is improved.