The Research On Image Denoising Based On Wavelet Transform

Digital images are often contaminated by noise during image acquisition and transmission. Noise degrades the image quality and causes some loss of information details. It is very important to suppress these noises in images before subsequent processing, such as image segmentation,edge detection,etc.But in practical applications, noise in the images is often a mixed one, which might be composed of Gaussian noise and impulse noise. Unfortunately, the existing denoising algorithms are often designed to deal with a single kind of noise, Gaussian noise or impulse noise.For the mixed noise, those algorithms can not achieve satisfactory effect.In recent years, with the continuous improvement of the wavelet theory, the wavelet analysis has been used in many fields. In the meanwhile, the wavelet has been widely used in image denoising and many image denoising algorithms based on wavelet transform have been put forward. The paper mainly does some studies in image denoising applications based on wavelet, and make a few alterations in the denoising method.First, this article carries on the comprehensive summary to the image denoising presentsituation and the commonly used methods. Wavelet threshold filter method in the wavelet filter technique, which obtains widespread application because of calculated simply. this article also Briefly introduce the basic theories of wavelet transformation and the wavelet transform of two-dimensional image.Next, this article introduce image denoising methods based on wavelet transform, and emphatically introduce wavelet threshold method.Then, this article introduce the common noise types and point out the methods of the denoising in present. Then mainly study and analyze several problems of wavelet threshold method in removing Gaussian noise, including the choosing principle of wavelet base of orthogonal wavelet transform, the selection of the threshold and the choosing ways of wavelet decomposition level. The experiment proves these discussion results are effective in denoising.this article also Study and analyze the filtering method which combines median filtering method with wavelet threshold shrinking method. Firstly, this method use median filtering method based on the impulse noise detection to detect impulse noise and filter wavelet. Then, the gaussian noise can be removed by using the wavelet threshold shrinking method.Finally, this article summaries the work and makes the forecast to the algorithm of imagedenoising further research direction.