Edge Detection Of Images Based On Dyadic Wavelet

Many fields related to image analysis are based on the edge detection of images,such as image segmentatio, recognition of target region, shape extraction from regional areas and so on. The edge detection of image is an important attribute for extracting image characteristics in image recognition.It is also the first step in image understanding and image analysis.Image edge detection is not only a hotspot in the discipline of image processing,but also a challenging research direction. In the image processing,the scale of the wavelet can adaptively adjust and detect according to the difference between the character in the local image.In recent years,with the development of wavelet theroy,wavelet transform according to its excellent properties has played a vital role in the field of image edge detection.Discrete wavelet transform has received much attention as a new powerful tool of image processing.There are two types of discrete wavelet transform: the biorthogonal wavelet transform and the dyadic wavelet transform. Since the biorthogonal wavelet transform is of down-sampling type and the demerit of being not shift-invariant, so precision of image processing isn't very good.However,the dyadic wavelet transform is shift-invariant and don't sample, so precision of image processing is better. Taking an existing image edge detecton method,for image edge detection research based on dyadic wavelet transform is truly rare.To search for more efficient edge detection method and further enrich the content of wavelet edge detection, we study on edge detection of images based on the dyadic wavelet transform theory.Mainly includes the folowing:(1) Introduce some sutra edge detection methods.Point out their advantages and disadvantages,for which advantages are inherited and disadvantages are improved on;(2) Make a systematic exposition about dyadic wavelet transform, emphatically introduce the dyadic wavelet transform fast algorithm:àtrousalgorithm;(3) Introduce a translation invariant dyadic wavelet transform,propose a kind of image edge detection method based on dyadic wavelet transform.Compare and analyse with the sutra image edge detection methods through simulate experiments. Simulation results show that this method has a better effect than sutra edge detection algorithms in noise immunity,detection accuracy and edge definition.It also shows that image edge detetion method based on dyadic wavelet transform proposed in this article is an effective method for image edge detection.