Research On Some Key Algorithms For The Image Processing

In recent years, the image processing technology has been developed quickly with the widening of image application fields. The image processing has been an important and useful technique in the fields of image understanding and computer vision. In the same time, traditional image processing methods based on space domain or frequency domain exist some shortcomings, which is very meaningful to improve the effect and speed of these image processing methods. The image processing is meant to use some algorithms to process a poor-quality image, which the purpose is that the processed image has higher definition and more understandability. It can not only be suitable for human to observe but also provide useful information for further applications, for example, image classification, image segmentation, object recognition, object detection, battle damage evaluation and so on.Now the image processing methods can be classed into two types. One method is image processing based on space domain, which the image is processed in space domain. The other is transforming the image from space domain to frequency domain, such as Fourier transformation. The transformed image is processed in frequency domain. Then the processed image is transformed to space domain again. These two methods are all useful, but each of them has advantages and disadvantages. In general, one method is only suitable for a certain class of images and only can improve the performance in a certain extent for the class of images.In this dissertation, the methods of image restraining noise, image enhancement, edge detection, edge thin and image zoom are all investigated and the improved methods are proposed. The main works are done in this dissertation have:1. A new method for calculating threshold according the property of people's vision is proposed. Based on the different sensitivity of people's vision at the different grey scale area, this method is proposed, which the property of people's vision grey scale is sufficiently considered. Since it is proposed according the property of people's vision, so it can be suitable for lots of visible light image. The threshold calculated by this method can obtain good effectiveness in image restrain noise, image enhancement and edge detection.2. According the property of people's vision grey scale and structure, an image enhancement algorithm with restrain noise function is proposed, which defines a new template to calculate gradient. This algorithm can not only enhance the vision effect of image, but also can restrain noise and enhance the detail signal. The effect of restraining noise is very good. On the other hand, the method can enhance not only the grey scale image, but also the color image, which can not distort the color.3. The rationality of model RGB in enhancing image is illustrated and the shortcoming of model HSI in enhancing image is proposed.4. For the sensitivity to noise of Robert edge detection algorithm, an improved Robert edge detection algorithm is proposed. It has the ability of restraining noise, and the detected edge is more smoother. For the complexity of Kirsch edge detection algorithm and Prewitt edge detection algorithm is comparatively high, they are analyzed and improved according the thoughts of some scholar. Improved their ability of restraining noise. At the same time, for the Prewitt algorithm the complexity of algorithm is declined too. Because the complexity of original edge-thin algorithm is high, its principle analyzed and its algorithm are simplified. The complexity of algorithm is declined under the condition of keeping the original effect.5. The algorithm of image zooming and image shrinking according the proposed model of spring is proposed. The results of experiment are very good.6. According to the principle of inertia in physics to trace the edge, Canny edge detection algorithm is analyzed and improved. The ability restraining noise is improved under the condition of keeping the original complexity, and the edge detected is smoother.7. Using the principle of disparity of between poor and rich of economics into the edge detection, Robinson edge detection algorithm is analyzed and improved, which the complexity of algorithm is declined. The ability restraining noise is improved more.All results of experiment are given for every algorithm of image edge detection, image enhancement and image zoom in the dissertation. Some worthy conclusions are also obtained through analyzing the experimental results and performance of objective evaluation the subjective analysis for the algorithms. All the experimental results show that the algorithms are effective.