Magnetic disk inspection using texture recognition

Quality control in magnetic disk production is a crucial issue, in particular the condition of the head disk 'interface' which is critical to the overall quality of the final product. The verification of this 'interface' has been complicated by advances in technology which have seen the height at which the head glides above the disk, the fly-height, reduce to micron order. This has necessitated inspection of the disks for defects of comparable magnitude. There is a growing need for visual inspection which is low cost and computationally fast in order to achieve total quality control. The micrograph of the disk surface is a natural texture and, whilst defect boundaries can be perceived by human inspectors, they do not correspond to a local discontinuity in intensity. Conventional edge detection operators are therefore unsuitable for segmentation. In this paper, segmentation is achieved via texture recognition. A texture recognition method based on a co-occurrence spectrum of n/sup th/ order is used and defect boundaries are defined by discontinuities in the texture within a window scanning the image.<
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