Digital-image-processing Instrument Research And Development

Digital Image Processing is an important course for university students majoring communicating engineering, computer technology, automation and signal processing. Based on Digital Image Processing, digital-image-processing-system has applied in some domain. In this paper, a digital-image-processing-instrument based on CCD camera is developed with programming tools of MATLAB 7.0. It has simple structure, better expansibility and better applicability.The significant advantage of the instrument is that USB interface is adopted so that the system has the function of plug and play. And the hardware part is small, which makes the system flexible in use and more convenient. It is also easy to expand the functions of the instrument with programming tools of MATLAB.The instrument software has the function of demonstration of basic knowledge of Digital Image Processing, i.e., it performs the functions of real-time collection and images saving, color change (brightness, binarization, RGB separation etc.), geometrical transform (rotating, mirroring), edge detection (Robert arithmetic operator, Sobel arithmetic operator, Prewitt arithmetic operator, LOG arithmetic operator, Canny arithmetic operator etc.), gray-scale image enhancement (histogram equalization, averaging filtering, median filtering), and binary mathematical morphology management (erosion, dilation, opening, closing, objects marking, Euler number calculation). In addition, it can show the gray-scale histogram of image and certain gray-scale value of an area specified.As a part of digital image processing applications, the instrument performs the measurement function based on image processing, i.e., dealing with the measurement of the dimensions of linear, triangle and rectangle objects after the CCD scaled by round objects with standard dimensions. The main principle is that the straight lines in the edge image are tested by Hough transformation, and then the geometry dimensions of these objects are calculated according tothe relevant relationship of the straight lines. Also, the instrument deals with the measurement of dimensions of round objects, whose diameters are calculated by least square fitting of edge images data.Finally, the reason causing measurement error is analyzed and its solution is given, and then how to correct it is provided.