Computerized system for digital subtraction, image processing and measuring of periapical radiographs

This paper introduces a computerized system for digital subtraction, image processing and measuring of periapical radiographs. This system has clinical applications. Based on the experimental test for this system, it has been found that the digital subtraction system for conventional radiography is very valuable for the diagnosis of minute bone lesions in the root side and apical part of the teeth. A new method for gray correction is presented and a new algorithm for image edge detection is designed. What is more, the principle of calibration and normalization for image measurement is also described and reasoned mathematically.