Unsupervised novelty detection using Gabor filters for defect segmentation in textures.

Gabor wavelets are applied to develop an unsupervised novelty method for defect detection and segmentation that is fully automatic and free of any adjustable parameter. The algorithm combines the Gabor analysis of the sample image with a statistical analysis of the wavelet coefficients corresponding to each detail. The statistical distribution of the coefficients corresponding to the defect-free background texture is calculated from the coefficient's distribution of the sample under inspection.

Modeling of woven fabric structures based on fourier image analysis.

The periodic woven structures of fabrics can be defined on the basis of the convolution theorem. Here an elementary unit with the minimum number of thread crossings and a nonrectangular two-dimensional comb function for the pattern of repetition is used to define woven structures. The expression derived is more compact than the conventional diagram for weaving, and the parameters that one needs to determine a given fabric can easily be extracted from its Fourier transform.

Referenceless segmentation of flaws in woven fabrics.

The automatic segmentation of flaws in woven fabrics is achieved by applying Fourier analysis to the image of the sample under inspection, without considering any reference image. No prior information about the fabric structure or the defect is required. The algorithm is based on the structural feature extraction of the weave repeat from the Fourier transform of the sample image.

Fabric inspection by near-infrared machine vision.

Fabrics that have superstructures of colored squares, bands, etc., superimposed upon the basic web structure can be advantageously analyzed by use of near-infrared (NIR) illumination and a conventional monochrome camera. The reduction in contrast of the superstructure signal in the NIR image facilitates inspection of the fabric's structure and defect segmentation.

Weave-repeat identification by structural analysis of fabric images.

Two descriptions of the image of a web structure, a convolution model and an additive model, in both the spatial and frequency domains, are combined in the design of a method to extract information about the fabric structure by image analysis. The method allows the extraction of the conventional and also the minimal weave repeats, their size in terms of number of threads, their interlacing patterns, and their patterns of repetition. It is applicable to fabrics with square and nonsquare conventional weave repeat.