Many manufactured fabrics do not necessarily have predefined and structured surfaces. The geometrical pattern, as seen in a close-up view, can take on many shapes which resemble stretch marks, scratches, and tears. For such non-structured surfaces, detection methods based on geometrical features are hard to apply; thus, fabric inspection is better accomplished via textural analysis, based on frequency domain characterization of the surface.
A careful analysis must be made in the frequency domain to be able to distinguish local patterns from anomalies. In the frequency domain, the information about the repetitive pattern, if it exists, should typically concentrate in one region of the Fourier spectrum, while anomalies are clustered in another. The problem of finding anomalies in our fabric inspection process is thus reduced to one of clustering the Fourier spectrum into frequencies of structured patterns and other frequencies carrying information of defects.
Both for textured and non-textured surfaces and fabrics, frequency domain analysis needs to be fine-tuned in order to capture the texture characteristics specific to each manufactured product. For this end, real computer vision experts are needed. With deep understanding of image structure, spectral analysis and manufacturing processes, RSIP Vision can construct the inspection algorithms which best fit your production line. Our algorithms have been successfully integrated in industrial applications for over two decades.