A fast approach for finding design repeat in textile rotary printing for fault detection

Speed is the most critical factor for real-time defect detection in fabric rotary printing systems. Most of the methods proposed in the literature work by acquiring an error-free image and registering this image with subsequent images captured during the production. In these methods, major time-consuming problem is to find the design repeat in the sample image before further processing. We proposed a fast method for finding the design repeat. The method is tuned up according to the textile printing domain. During the printing process, the fabric moves in a horizontal direction, so the image registration can be restricted to the same direction. To further speed up the process, the image registration method is applied using few initial pixel columns of the reference image with the sample image. This bunch of selected columns of the reference image is matched with the same number of columns selected from the sample image by moving this bunch on the sample image column by column. The maximum matching position is marked as a start of the design repeat. Since the repeat size is always fixed, we can extract the complete design pattern from an acquired image for further processing of fault detection. Experimental results on different fabric designs using the above-mentioned method are very promising.