Study on a Fast Method for Sub-Pixel Edge Detection

Aimed at the problem that its difficult to improve the identify precision of the linear CCD scan image, a novel fast sub-pixel edge detection method for image measurement is proposed, the basic process is like this: firstly, according to the step gradient features, automatically calculate the pixel-level border of the CCD image. Then use the wavelet transform algorithm to divide the image´s edge location in sub-pixel level, thus detecting the sub-pixel edge. Key technologies of CCD scanning polymer film materials defects detection are deeply investigated in this thesis. A polymer film materials defects detection system is established. The experimental results demonstrated that defects within 70 μm~1000 μm were inspected effectively by the CCD scanning defects inspection instrument, that this method has a repetition error no more than 0.02 pixels, with high precision and good anti-noise ability.