Sub-pixel measurement system can, to
some extent,
compensate the margin positioning error caused by hardware limitation. A kind
of sub-pixel measurement system of circle outer diameter based on Zernike moment is established. Sub-pixel edge detection algorithm of circular workpiece
based on Zernike moment is proposed and further positioning of edge points in
the gradient direction by the adoption of quadratic polynomial interpolation is
conducted. Finally, circle outer diameter measurements of sub-pixel accuracy
are obtained by using least square method fitting the edge points. The
experiment results show that the measurement accuracy of system is high, which
meets the requirement of high accuracy measurement of circular workpiece.
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Jensen, K. and Anastassiou, D. (1995) Subpixel Edge Localization and the Interpolation of Still Images. IEEE Transactions on Image Processing, 4, 285-295.
Shan, Y. and Boon, G.W. (2000) Sub-Pixel Location of Edges with Non-Uniform Blurring: A Finite Closed-Form Approach. Image & Vision Computing, 18, 1015-1023. https://doi.org/10.1016/S0262-8856(00)00040-8
Xin, Y., Liao, S. and Pawlak, M. (2004) A Multibit Geometrically Robust Image Watermark Based on Zernike Moments. IEEE International Conference on Pattern Recognition, 4, 861-864.
