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Cascaded integrator comb (CIC) filters are in wide use in oversampled analog-to-digital converters. In this study, the authors advances three new cascaded decimator structures with integer coefficients designed using a polynomial factorisation approach. Each one of the designed decimators shows better stopband attenuation for a given order and decimation factor than the CIC or recently proposed generalised comb filter (GCF) and may not require any prefilter for performance enhancement. A fourth new decimator structure is a hybrid between the CIC and GCF with coefficients approximated by integers. Decimator power dissipation analysis and optimisation have previously been done either by counting the number of additions per sample rate or by focusing on register clock distribution. The authors propose a new metric for estimating the power dissipation of a filter structure from its architecture accounting for dissipation both in the adder cells and the flip-flops. The authors show frequency domain characteristics and compare power dissipations of all the new structures using a representative example.

This study presents a method to resize images by a rational factor of P/Q in the discrete cosine transform (DCT) domain, where P and Q are relatively prime integers larger than 1. Our method extends on the prior work of Mukherjee and Mitra, which utilises the spatial relationship of DCT coefficients between a block and its sub-blocks. To resize images by a factor of P/Q, the images are first up-sampled by a factor of P and then down-sampled by a factor of Q. Although this method produces resized images with good visual quality, it requires high computational cost. In this study, the authors generalise an observation found in the spatial relationship of the DCT coefficients between a block and its sub-blocks. Subsequently, a sparse matrix representation is derived from this observation to reduce the computational cost of the proposed method. To further reduce computational cost of the proposed method, a subset of up-sampled DCT coefficients is used in the down-sampling operation. From various experiments, the authors have determined the lowest number of up-sampled DCT coefficients to be used in the down-sampling operation without affecting the visual quality of the resized images. As compared to existing methods, the proposed method requires lower computational cost and produces resized images of good visual quality.

A simple two-stage multiplierless cascaded-integrator-comb (CIC)-based decimator is presented. The first stage is a cascaded CIC filter whereas the second stage is a cascaded CIC filter and a second-order multiplierless compensator. The proposed decimator can be realised without filtering at high input rate by making use of the polyphase decomposition of the comb filter in the first stage. The proposed filter exhibits high aliasing attenuation and a low passband droop. The design parameters are the decimation factors, M 1 and M 2 , numbers of cascaded CIC filters L and K , and parameter b of the compensator.

A simple second-order sine-based CIC (cascaded-integrator-comb) compensator is presented. The design parameter is the integer b, which depends on the number K of the cascaded CIC filters. The proposed filter performs compensation efficiently using only three additions/subtractions.

The authors previously considered the application of multilayer perceptrons (MLPs) to block coding at the sensor level of modern imaging systems, and have proposed analogue encoders with transistor-count complexity that is low enough to suit focal-plane implementation. In the paper, they extend the on-sensor block coding MLP study, to include a statistical analysis of the MLP sensitivity to implementation errors occuring in standard CMOS fabrication processes. Employing simple offset models, a comparison is made of the MLP with other block encoders based on full-search entropy-constrained vector quantisation (ECVQ) of the data, and it is verified that the MLPs are less sensitive over a wide range of rate-distortion compression points. By introducing a realistic linear model that takes into account sensitivity and the complexity performances for both systems, the authors verify that, for MLPs, the sensitivity becomes less dependent on the complexity as the expected quality loss is allowed to increase. Without setting a limit on the expected quality loss, the MLPs are consistently better than the ECVQs, both in terms of sensitivity and complexity for a precision equivalent to 6 bits.

Using the spatial relationship of the block discrete cosine transform (DCT) coefficients and subband approximations, algorithms for image halving and doubling operations are presented. The computational steps identified in the process provide a general framework for image resizing operations. Some of the previously reported image halving and doubling algorithms are shown to be special cases. The proposed approach is general enough to accommodate resizing operations with arbitrary factors, namely with integral and rational factors. The application of these methods to the conversion in the compressed domain of images (video frames) from one format to another is demonstrated.

A new low sensitivity second-order bandpass digital filter structure is presented. The proposed structure has the smallest absolute angle, sensitivity and a moderate radius sensitivity for the pole angle /spl theta/ in the range 0.38/spl pi/ /spl les/ |/spl theta/| /spl les/ 0.44/spl pi/ and 0.56/spl pi/ /spl les/ |/spl theta/| /spl les/ 0.62/spl pi/ and for the radius in the range 0.5 /spl les/ r < 1.

A saturation-based adaptive gradient interpolation algorithm is developed for Bayer pattern images obtained in single-sensor digital cameras. The proposed algorithm uses the concept of pseudo-saturation for 2/spl times/2 blocks of the image. The algorithm adapts the scheme of interpolation based on the classification of the pseudo-saturation of Bayer pattern images. Compared with other algorithms, the proposed method preserves fine details, reduces false colours, and distortions around edges and sharp features of the colour image reconstructed from different kinds of Bayer pattern images.

A simple method of active RC realisation of a voltage-transfer ratio is proposed. The final structure employs a single operational amplifier.

Two nullator-norator equivalent representations of the non-reciprocal negative-impedance invertor (z11 = z22 = 0, z12 ≠ z21, and z12/z21>0) are described, with several transistorised-circuit realisations of these devices.

A simple method of designing an all-pass network is presented. Final realisation incorporates a single nonideal current-controlled current source, which in most applications can be replaced by a single-transistor circuit.

A new method of realising a voltage-transfer-function vector by means of an active network containing RC 1-ports and a single operational amplifier is presented.

Three nullator-norator representations of gyrators are presented. Each of the equivalent representations leads to two three-transistor realisations of the gyrator. Two of the transistorised gyrator circuits appear to be new.

A theorem on positive real functions having all poles and zeros on the negative real axis is proved.