Selectively filtering image features using a Percentage Occupancy Hit-or-Miss Transform

The Hit-or-Miss Transform (HMT) is a well known morphological transform which can be used for template matching and other applications. Recent developments in this area include extensions of the HMT which have employed a variety of techniques in order to improve the noise robustness of the transform. Rank order filters feature heavily in these approaches, and recently, a novel design tool, known as a PO plot, has been introduced. This tool can be used to determine the optimum rank parameter when using these extensions of the HMT to locate features in noisy data. In this paper, the properties of the PO plot are exploited in such a way that an extension of the HMT, known as a POHMT, can be used as a discriminatory filter which selectively marks or discards features in an image. This paper summarises the POHMT, and the PO plot, before demonstrating how these can be used to implement a discriminatory filter. This filter is then shown to produce promising results when applied to the problem of selectively detecting dice in images.