Sub-Pixel Subdivision Research on Linear CCD Screen Images

Z. Lei, H. Lv (PRC), and P. Bhattacharya (Canada)

Keywords

Subpixel subdivision, Threeorder spline interpolation, Multiscale edge detection, Linear CCD optoelectronic screen, Image processing

Abstract

Based on intersection measurement principle, we use two high speed linear CCD cameras consisting of optoelectronic system to measure the coordinates of the high speed object while it passes through the screen. Its testing accuracy interrelates with object images edge. When the object passes far away the centre region of big size screen, the images edges become blurred. The result of the commonly edge detection operator exist a bigger error. In this paper we present a multiscale method that combines the Robert operator with three-order spline interpolation to compute the edges in promptly and accurately. Using Robert operator detect the image to obtain approximately edges point, take that as center, and then three-order spline functions interpolate the image that cover 7 gray data. The extremums of the spline function occur at the grid point. The points correspond with the sub-pixel edges of the image. The practical measure results prove this method and improve the coordinates detection precision 3.1mm.

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