The Application Research Of PVC Product Inspection By Edge Detection

Computer visual inspection is rising and advancing. It brings a new way to auto-measure. And edge detection is one of great important parts in computer auto visual inspection. Image edge contains much useful information, and it is very important to pattern recognition, computer vision, image analysis and image code. This thesis summarized the current state and development of edge detection in china and abroad.There are many methods of edge detection. According to practical task, we choose some classical methods of edge detection including first differential(Roberts operator, Sobel operator and Prewitt operator), second differential(Laplacian operator and Kirsch operator), LOG filter and Canny operator. They are studied in theory and practice applying.Wavelet transform is a kind of time-frequency analysis method in signal processing and is becoming more and more popular during these years. Its multi-scale property, localization both in time and frequency domain, sensitivity to the abrupt change of signals, and good to denoising make it an ideal way for edge detection. We use B-spline biorthogonal wavelet to form filter groups, and explore application of edge detection based on multi-scale wavelet transform.A analytical and processing software is designed under the environment of Visual C++6.0. Firstly, color intensity is transformed to gray intensity and image is filtered out some noise. Secondly, we use some above classical methods of edge detection. And we use multi-scale wavelet transform to measure the edge of PVC product in Matlab. After comparing these methods, we draw a conclusion: multi-scale wavelet transform is a better method in detecting edge of PVC product. Finally, we make the qualitative analysis of edge detection.