In the procedure of image preprocesses, some image preprocesses algorithms such as Gray Balance, Image Smooth, Median Filter are used for enhancing the SNR (Signal Noise Ratio) of the PCB image.

• 在图像的预处理方面,为了提高印刷电路板数字图像的信噪比,采用了灰度修正、图像平滑、中值滤波等优化图像质量的预处理算法;