Research On Image Distortion Correction Algorithm Of The Wide-Angle Lens

With the development of the fields of intelligent and a variety of applications of related equipment, cameras is used more and more popularly in national military, urban transportation, medical system, as well as in People's Daily life.In order to obtain a larger field of view for image information, people often use a Wide Angle lens.However, due to the structure of the Wide Angle Lens itself, it makes the images got by the lens contain certain non-linear distortion so that the location accuracy of geometric objects in the image is affected and it lost the high application value in the image measurement, recognition, and other areas where high degree of accuracy is needed.So you need to correct the image distortion.In recent years, the image distortion correction which has a certain theoretical significance and wide application prospect is a hot issue in the field of image processing applications.Through the analysis of the principle of optical lens imaging and the distortion, studying and completing the traditional image distortion correction algorithms, such as Grid template correction algorithm.On the base of this,bringing in the introduction of concentric circles template correction algorithm.Concentric template correction algorithm is based on the radius of concentric circles which is a kind of simple and convenient algorithm.In the algorithm,we use multiple evenly spaced concentric circles as a template, and then use the camera that have the properties of wide Angle camera to get a template image which contains distortion.We will extract the the corner points in the distorted image to fit the radius of each concentric circle in order to get the size of radius of each concentric circles after do some pretreatment,such as filtering, corrosion. Then using the polynomial curve fitting technology to solve the the mapping relationship between the radius of concentric circle that is distorted and the ideal radius so that the distortion correction model is established. According to the good correction model, calculating the coordinates of the ultimate ideal point, and by using Bilinear-interpolation algorithm to complete the correction of the image's gray scale so that we will finish the work for image distortion correction.In the algorithm, the lens optical center is needed to aim the image geometric center while getting the image of the template.And if the registration is not accurate,it will lead to centrifugal distortion.To overcome the problem, we have introduced a method which contains a alignment with cross reference line, which can effectively avoid the centrifugal distortion in image acquisition, and reduce the scanning steps of concentric circles,as well as effectively improve the speed and accuracy of correction of the algorithm.After doing some experiments for all sorts of the images which are got by the Wide Angle Lens, including the distorted template image with concentric circles, the images that contains linear edge distortion and the grid template image, it shows that the algorithm has a good correction effect and it's algorithm efficiency is efficient.