Pathamadi V. Sankar

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A ``piecewise heuristic'' follower of the boundaries of difficult-to-notice nonoverlapping blobs in digitized images is described. The technique was tested on 324 X-ray images of candidate lung nodules from eight radiographs with good results. This technique is several times faster than earlier detectors of the boundaries of lung nodules, while maintaining(More)
We prove that the Toeplitz binary value matrix inversion associated with mth order E-spline interpolation can be implemented using only 2 (m + 1) additions. We develop pipelined architectures for real time B-spline interpolation based on simple running average filters. We also show that an ideal interpolating function, which is approximated by a truncated(More)
The B-spline functions are used to develop recursive algorithms for the efficient implementation of two-dimensional linear digital image filters. These filters may be spatially varying. The B-splines are used in a representation of the desired point spread function. We show that this leads to recursive algorithms and hardware implementations which are more(More)
A detailed error analysis for the dual-sampling region-ofinterest X-ray tomography is presented. Simulation studies are used along with a range of sampling rates to quantitate the amount of sampling errors within the region of interest. It is shown that as the rate of sampling outside the region of interest becomes sparse the amount of sampling errors(More)
Ehrich and Foith have proposed an approach to the hierarchical representation of waveforms based on peak dominance relations. This correspondence proposes an alternative approach, derived from concepts of fuzzy connectedness. It also discusses the possibility of extending this approach to the description of curves and of images.
We study the instantaneous frequency of a signal which is formed by the summation of a sinewave and a bandlimited signal. We refer to the composite signal as a sinewave squelched or simply a squelched signal. We study the behavior of the squelched signal at its real zeros and extrema. In particular when the sinewave frequency is equal to the largest(More)