Accurate Localization Algorithm for Rectangle Mark Based on Spatial Interpolation Technology and Combined Detection Method

The precise center position and orientation of the rectangle mark play an important role in the localization of printed circuit board (PCB) and electronic components mounting. This paper presents an effective and practical method to detect the accurate orientation and calculate the precise center coordinates of the rectangle mark in the captured image. It includes the construction of the high resolution image by the edge-directed spatial interpolation and the measurement of the rotation angle and the position for the rectangle mark based on the Hough transform and the template matching. The novel hybrid scheme has improved the positional accuracy of the mark to approximate which is equal to a quarter of the side of the pixel in the original captured image and has made the errors in rotation angle to be within degrees. Experimental results demonstrate that the approach has achieved noticeably better performance than the traditional template matching and other methods in the precise and the computational complexity.