A Digital Algorithm for Precipitation Self- Recording Paper

Fengwen Zhang

Shanghai University Shanghai, China

Abstract: The main steps of digital algorithm for precipitation self-recording paper are image rotation correction, coordinate line extraction, tracing curve and extraction. First of all, Canny operator detect the edge of precipitation self-recording paper, and get the angle of image rotation by Radon Transform, and then make a rotation, it can correct the inclined image. Secondly, in accordance with the rule of the lines, it takes advance of projection analysis of image to find the correct location of the axis. Thirdly, the image of precipitation selfrecording paper is threshold segmented by Kittler algorithm, and eliminated the interference connected component by morphological filtering. Finally, bianry image is intensified by Gabor filtering algorithm, and we can extract the center line of the precipitation curve according to the maximum vertical position using Skeleton method. And then we get the real data of one minute, ten minutes and one hour from the image of precipitation self-recording paper.

Keywords: Gabor filtering; precipitation self-recording paper; threshold segmentation; projection analysis