Ting Chen

Publication Date


Document Type


First Advisor

Bow, Sing-Tze, 1924-

Degree Name

M.S. (Master of Science)

Legacy Department

Department of Electrical Engineering


Image processing--Digital techniques; Crystals--Defects


Detection of tiny defects is the key quality control in quartz crystal production. Difficulties in these inspections are due to the fact that such defects are usually so thin and short that they are almost visually indiscernible from the blurred textural background of quartz crystals unless a special illumination and torsional viewing mechanism are provided. The work presented in this thesis is an application of digital image processing techniques to the automatic detection and delineation of these indiscernible imperfections to assure high quality in crystal production. Algorithms and methods are discussed and proposed in the thesis in detail. The special approach suggested in this paper has been applied to the analysis of various textural images of real quartz crystal samples. Experimental results obtained show that tiny edge cracks and center scratches were successfully detected. Other useful information, for instance, the type of images, the type of defects, the location of defective areas, and the shape of defective areas, can be also obtained on the system. This approach has been suggested to the automated inspection system for the detection of indiscernible defects in quartz crystal production. The approach can be also applied to the analysis of various textural images, like fabrics, carpets, lumber, etc. It can also be used for the detection of other imperfections which are not visible to the naked eye.


Includes bibliographical references (pages 73-76)


x, 117 pages




Northern Illinois University

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