Infrared Image Processing In Real-time Detection

The technology of IR and thermal image can be used in detecting the fault of electronics in virtue of the high capability of thermal instruments and digital image process. In the middle 1960s, it began to be applied in detecting the fault of electronic facility in foreign countries. In the 1970s, thermal instrument had been installed in helicopter to detect the connection of power line and the determinant standard about infrared test had been established. In the middle 1980s, IR technology had a comprehensive application on the fault of Print Circuit Board (PCB). But there are many shortages in the traditional technique because it is invasive. The research about the non-invasive inspection of PCB that is based on IR image is introduced. The detection principle, the components of hardware and software are introduced in this paper. Some key technical problems and the project of software are presented in detail: Graphics of User Interface (GUI) of the projection, Gray Scale Transformation (GST), image contour extraction through edge detection algorithm based on the approaching contour optimization, image registration based on corner detection, the position of hidden trouble PCB through add-minus algorithm image. In the first chapter, digital image process is introduced, including the application. The second chapter gives the history background, development and principle of the IR test. In the third chapter, the application of IR test of PCBs,hardware and software are analyzed. Hardware is composed of four elements: computer, IR thermal instrument, PCB, and power supply. In the fourth chapter, the executive process of software and the realization of image process function are introduced. A perfect GUI is programmed in VC++6.0. The function class of Device-Independent Bitmap (DIB) is defined to realize some basic functions. 256 colors palette can be transformed to gray scale palette based on the corresponding relationship of gray scale and RGB colors. Contour extraction through edge detection algorithm is based on the approaching contour optimization. This arithmetic is better than the traditional method, and it has advantages to a certain degree because the progress of edge extraction is in harmony with the contour track. Particularly, based on a fast corner detection algorithm on gray level, a new method of image registration is presented. Corner information can be achieved by scanning along the circle. After the corners of different frames of the same scene are detected, the matching corner pairs between these frames can be found. Based on these pairs, initial registration parameters can be estimated. And then, an iterative scheme is performed to refine these registration results. The experiments show that this method has no restriction to rotation angle between the frames and is computationally efficient and that the registration results are of high precision. In term of add-minus algorithm, the fault position of PCBs can be located.