Detecting defects in fabric with laser-based morphological image processing

Morphological operations such as erosion and opening are applied to both di rect and spatially filtered images of test fabrics to identify defects. Det ecting defects morphologically on spatially filtered images of fabrics prod uces better results, particularly when the fabric is fine and contains defe cts of small size. The diffraction pattern of the test fabric is obtained o ptically by illuminating it with a collimated laser beam. A spatial filter is placed at the Fourier plane to remove the periodic grating structure of the fabric from the image. Morphological operations with a critically selec ted structuring element are then applied to the image after suitable pre-pr ocessing.