The Research Of Algorithm For Image Edge Detection Based On Phase Information

Edge is one of the basic characters of an image, which offers people important parameters to describe and recognize objects in an image. Edge detection is one of the most fundamental operations in image processing, image analysis and computer vision. It is one of the basic methods for pattern recognition and image information extraction. Images obtained from real-world scenes are generally buried in noise. Both edges and noise may be obtained in an attempt to detect edges from an image with a large amount of noise. How to detect edges reliably and accurately in the presence of noise has remained an important issue in the field of edge detection.Firstly, the thesis starts with the mathematical thought of image edge detection, and studies on the characteristics of traditional edge-detection algorithm. The focus is the anti-noise property of traditional edge-detection algorithm. During this process, the analytical method makes use of traditional algorithm to detect image in which contains Gaussian White Noise.Secondly, the thesis researches on an algorithm for image edge detection based on phase information, which is phase congruency. After verifying the importance and stability of phase information in image processing, the thesis studies on phase congruency function. Algorithm for image edge detection based on phase information in wavelet domain is presented. This thesis which analyses the relation between phase congruency function and local energy function chooses Gabor wavelet transform to calculate local energy function, and at last uses phase congruency function to detect object image edge. This method needs hypothesize nothing about images in advance. It is to pick up target image edge based on the signal phase's trend toward consistency in Fourier transform domain. It can not only detect step characteristic and linear feature but also can detect Mach band phenomena on account of the characteristics of human visual perception, so it is possessed of stronger generality.At last, the thesis makes use of algorithm for image edge detection based on phase information to obtain image edge with piston as detected object, then using Hough transform measures diameter parameter of workpiece. The experimental results prove that the algorithm for image edge detection based on phase information can bring into the effect. Moreover the algorithm effectively detects image edge and exactly gets the diameter parameter. It indicates that the algorithm for image edge detection based on phase information is superior.