Rapid Vision Measurement of LED Die Array Based on Cross Correlation in Frequency Domain
LI He-xi1,HAN Xin-le1,YANG Tie-niu2
1.School of Computer Science, Wuyi University, Jiangmen, Guangdong 529020, China
2.School of Mechanical and Electrical Engineering, Wuyi University, Jiangmen, Guangdong 529020, China
Abstract A rapid template matching method based on cross correlation in frequency domain(CCFD) is presented for real-time visual measurement of light-emitting diode (LED) die. First, the gray value of LED die array image is normalized by a recursion-sum algorithm in spacial domain, and then using fast Fourier transform the CCFD is carried out between LED die array image and die template to rapidly locate all pixel coordinates of LED dies. The higher measurement efficiency can be obtained because of omitting image normalization for clear binary images of LED die array. Experimental results of complex LED die images show that the measurement efficiency is far higher than conventional normalized cross-correlation(NCC) algorithm, and is only half of consumed time to compare with the sequential similarity detection algorithm(SSDA). The proposed CCFD algorithm can be used for rapid LED die measurement in LED sorting or die-bonding system.
LI He-xi,HAN Xin-le,YANG Tie-niu. Rapid Vision Measurement of LED Die Array Based on Cross Correlation in Frequency Domain[J]. Acta Metrologica Sinica, 2018, 39(4): 476-480.
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2018, Vol. 39 
