A matching method based on marker-controlled watershed segmentation

A new template matching method that is based on marker-controlled watershed segmentation (TMCWS) is presented. It is applied to recognize numbers on special metal plates on production lines where traditional image recognition methods do not work well. In contrast to previous matching algorithms, TMCWS firstly creates a marker image for each pattern, and then takes both the pattern image and its corresponding marker image as a template window and shifts this window across a gradient space or an unknown image pixel by pixel to do a search. At each position, the marker image is used to try to extract the contour of the target object with the help of marker-controlled watershed segmentation, and the pattern image is employed to evaluate the extracted shape in each trial. All the pattern images and their corresponding marker images are tried and the pattern that best matches the target object is the recognition result. TMCWS contains shape extraction procedures. Experiments are performed with this method on nearly 400 images of metal plates and the test results show its effectiveness in recognizing numbers in noisy images.