Periodic Pattern Inspection Using Convolution Masks

A two-dimensional (2-D) convolution mask is proposed for detecting the location of irregularities and defects in a periodic two-dimensional signal or image. In this approach, defects on a 2-D test image is automatically filtered out by a 2-D convolution mask implementing the spatial filter. This approach is reliable and computationally efficient. Besides, unlike the traditional die-to-die approach, it can avoid all troubles in a database image, a scaling or alignment procedure.