Edge Detection Using Canny Operator with Sub-pixel Refinement for Dimensional Measurement

Dimensional measurement of circular and hole-type workpieces represents a critical workflow in quality control. The system employs the Canny edge detection operator for initial boundary identification, followed by sub-pixel refinement algorithms to enhance measurement precision. The implementation typically involves multiple processing stages: Gaussian filtering for noise reduction, gradient calculation using Sobel operators, non-maximum suppression, and dual-threshold hysteresis for edge tracking. For sub-pixel refinement, techniques like Gaussian interpolation or moment-based methods are applied to achieve finer edge localization. A graphical user interface (GUI) facilitates intuitive operation and real-time visualization of measurement results, allowing users to configure parameters such as Canny thresholds and sub-pixel computation methods. The system achieves a measurement accuracy of 0.1mm through careful calibration and optimized image processing pipelines, ensuring reliable dimensional assessment of circular profiles and internal bore geometries. Key functions include automated edge coordinate extraction, least-squares circle fitting for roundness evaluation, and statistical analysis of diameter measurements across multiple sampling points.