Video Filtering Research Articles

A method for tracking rats in a complex and completely dark environment using computerized video analysis

The automated tracking of rodents in open field environments has become a standard laboratory technique for the investigation of the effects of drugs, novel therapeutic interventions and genetic mutations on behavior. Here, we develop an extension of this technique that permits tracking in full darkness through a complex (‘enriched’) environment comprising naturalistic structures such as tunnels and hides. To eliminate unwanted light reflections and tape noise, we developed a unique video filter that combines the advantages of differential and non-differential filtering. This filter enabled the tracking of albino rats against a relatively dark background to an accuracy of approximately 97% compared to hand tracking of the same animal, irrespective of whether the rat was inside a hide box or tunnel or out in the open field. The system as a whole can be easily deployed using standard PCs and inexpensive infrared cameras and lights.

Deblocking filter for low bit rate MPEG-4 video

Increasing the bandwidth or bit rate in real-time video applications to improve the quality of images is typically impossible or too expensive. Postprocessing appears to be the most feasible solution because it does not require any existing standards to be changed. Markedly reducing blocking effects can increase compression ratios for a particular image quality or improve the quality with respect to the specific bit rate of compression. This paper proposes a novel deblocking algorithm based on three filtering modes in terms of the activity across block boundaries. By properly considering the masking effect of the human visual system, an adaptive filtering decision is integrated into the deblocking process. According to three different deblocking modes appropriate for local regions with different characteristics, the perceptual and objective quality are improved without over smoothing the image details or insufficient reducing the strong blocking effect on the flat region. According to the simulation results, the proposed method outperforms methods of deblocking MPEG-4 with respect to peak signal-to-noise ratios and computational complexity.

41.2: The Effect Of Edge Filtering On Vision Multiplexing

We developed a video filter that produces cartoon-like images consisting of bipolar white and black transitions at luminance edges of the input video, for use in augmented-vision devices. When tested in an inattentional blindness experiment it had no effect on the detectability of unexpected events, but did affect speed of responses to the attended task Response time improved when the unattended scene was filtered and degraded when the attended scene was filtered.

Synthesis of hardware models in C with pointers and complex data structures

One of the greatest challenges in a C/C++-based design methodology is efficiently mapping C/C++ models into hardware. Many networking and multimedia applications implemented in hardware or mixed hardware/software systems now use complex data structures stored in multiple memories, so many C/C++ features that were originally designed for software applications are now making their way into hardware. Such features include dynamic memory allocation and pointers for managing data. We present a solution for efficiently mapping arbitrary C code with pointers and malloc/free into hardware. Our solution, which fits current memory management methodologies, instantiates an application-specific hardware memory allocator coupled with a memory architecture. Our work also supports the resolution of pointers without restriction on the data structures. We present an implementation based on the SUIF framework along with case studies such as the realization of a video filter and an ATM segmentation engine.

Compliance Conducted EMI Analysis—A Case Study

The compliance conducted EMI measurement analysis primarily depends on the selection of specific impulsive bandwidth to measure emissions in the frequency range of interest. Such bandwidths are specified in International special committee on radio interference (CISPR) specification no. 16–1. The other factors which can influence conducted EMI measurement analysis are video bandwidth (VBW), sweep time (ST), amplitude mode selection (linear or logarithmic) & RF input attenuation of EMI receiver. This paper deals with measurement analysis of conducted EMI, where peak emissions exceed average regulatory limits but remain below quasi-peak limits. In such case, average measurement analysis is recommended. Subject analysis can be carried out either in automated or manual mode. But there are some older versions of EMI receiver, which measures average conducted EMI in manual mode only. Such average measurement analysis is employed by video filtering technique. This paper intends to find out influence of various parameters on conducted EMI manual average measurement analysis.

Top-down design of a switched-current video filter

A case study for the design of switched-current filters is presented. While the emphasis is on the step-by-step numerical design of a video filter, the design flow is applicable to any switched-current filter. The chosen design example is a low pass elliptic ladder filter with the following specification: passband 0.5 dB equiripple, stop-band attenuation > 30 dB, –3 dB frequency of 8 MHz, sampling frequency of 80 MHz, signal-to-noise ratio of 60 dB. All aspects of the design are covered from filter specification, through filter synthesis, circuit definition and finally transistor sizing for CMOS implementation.

Current-mode group-delay equalisation using pole–zero mirroring technique

The authors describe an efficient method for designing current-mode group-delay equalisers. The method is based on introducing zeros into the right-hand s-plane by mirroring the poles of an LC ladder network. This is achieved by developing a current-mode model capable of implementing the pole–zero mirroring technique. Using multiple-output OTAs and grounded capacitors, the model is used to derive an nth-order active group-delay equaliser structure which is simpler, has better correction accuracy and is less sensitive when compared to cascade approach based equalisers. The equaliser design involves two optimisation algorithms. The first algorithm generates a polynomial function whose group-delay response equalises the filter response. The second algorithm produces the equaliser component values as a result of solving a set of nonlinear equations generated from coefficient matching the equaliser transfer function to the polynomial generated from the first algorithm. Simulated results with CMOS OTAs and measured results based on discrete realisation of a 6th-order equaliser are included. The results demonstrate that the equaliser can effectively compensate the delay characteristics of a 7th-order 5.75 MHz lowpass elliptic video filter to < 5 ns ripple over 90% of the filter passband.

Single-chip BiCMOS multistandard video processor

A cost effective single-chip BiCMOS multistandard video processor has been developed. Various functions (video filters and chroma delay lines) have been integrated. The entire circuit is adjustment-free and it can be applied to all of the sub-carrier frequencies with one peripheral crystal.

SC realization of antialiasing CCIR-601 video filters

Switched-capacitor circuits as discrete-time analog devices are especially suited for the signal processing tasks occurring when interfacing analog and digital systems. The major obstacle towards the use of standard CMOS technology for SC video filters is the limited speed of high-gain CMOS op-amps. This limitation however can be overcame with some design ingenuity, as in the application considered in this work. Recommendation CCIR-601 prescribes to prefilter luminance and color-difference signals with filters characterized by tight group-delay specifications. In this work we consider the realization of the color difference prefilter H/sub a/(s), which is currently available only in discrete-component (and therefore very expensive) implementations, with an equivalent system formed by the cascade of two integrated filters, namely a continuous time filter H/sub 1/(s) and a SC filter H(z). This type of implementation can be applied to the luminance prefilter as well. Since CCIR Recommendation 601 prefilters are at the front-end of every digital television system, there are opportunities for their large-scale production within which the economical advantages of the proposed integrated solution are apparent. >

Vlsi programmable digital filter for video signal processing

High speed digital filtering is required in real time video signal processing, as well as high order filters are needed to match television studio signal quality. The hardware complexity involved by such system constraints may be faced by a two-fold approach, concerning both the architecture and the technological aspects of a specific electronics device devoted to the above task. This article deals with a processor especially developed for the purpose of fast digital video signal applications, such as filtering, equalization, interpolation and so on. The nonrecursive transposed F.I.R. (Finite Impulse Response) structure has been selected, which exhibits a linear phase behavior. A novel approach has been developed for the multipliers implementation, by optimizing an EPROM based look-up table storing the products between all video samples and the filter coefficients significant bits, resulting in a programmable system. TheProgrammable Filter Processor has been designed with a high level of parallelism and pipelining and a 1.2 µm CMOS EPROM, single metal technology has been employed for the integration process of the chip. This has been successfully production-tested for 40 Msamples/s throughput rate, thus both allowing to meet most video filtering applications and demonstrating the potentialities of nonvolatile memory technologies in embedded applications. Moreover multiple devices can be interconnected to yield multiprocessor structures for more demanding performances such as, cascaded or longer filters, input signal precision extension, computation improved accuracy, increased throughput rate, and two-dimensional signal processing.

A new single-chip video signal-processing LSI for the high-band 8 mm camcorder

A novel single-chip video LSI for the high-band 8-mm camcorder has been developed. This LSI has succeeded in reducing the number if ICs, pins, and components, and the power consumption drastically. Three ICs, six external video filters, and other peripheral components have been built into this LSI, allowing 109 components to be eliminated and all the adjusting points to operate in EVR (electric variable resistor) operation. Consequently, using this LSI, a compact, low-power, high-picture-quality Hi8 camcorder can be achieved. This chip performance is summarized. >

General purpose video processor for high speed filtering applications

A video processor that allows the implementation of high-speed finite impulse response (FIR) video filters is described. This is made possible by using a parallel architecture implemented on 1.2 mu m CMOS EPROM technology. This solution makes it possible to overcome classical DSP (digital signal processing) problems such as processing speed, number of taps, flexibility, and volatility. The maximum achievable throughput in a single-chip configuration is 30 Mwords/s; such a processing speed allows comfortable use of the chip in the field of Rec. 601 (13.5 MHz sampling rate) while, in the case of HDTV (high-definition television), multiple-chip architectures may be configured to obtain a higher sampling rate.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Design considerations for high-frequency continuous-time filters and implementation of an antialiasing filter for digital video

An approach that has made possible the integration of video frequency continuous-time filters with wide dynamic range is discussed. The tuning scheme necessary to maintain the stable and accurate frequency response in the presence of temperature variations, process tolerance, and aging is described. Detailed design techniques specific to high-frequency operation are introduced to implement a 5-V, seventh-order elliptic analog magnitude filter for antialiasing in digital video applications. The filter, based on a G/sub m/-C technique, exhibits a dynamic range of 61 dB and dissipates a power of 75 mW. Ninety-two chips from various wafers and two different process runs were tested. Seventy-five percent of the fabricated chips were functional, and 63% of them met the commercial-grade specifications in spite of an error in the layout which forced the phase control circuitry to perform suboptimally.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Design of low–loss saw filters employing distributed acoustic reflection transducers

AbstractAs a means to reduce the loss in an SAW filter, the IDT (interdigital transducer) called the internal reflection‐type transducer has been studied extensively recently. This IDT is believed to be useful as a filter for video and broadband data transmission since it is simple in structure and has low loss over a broadband while its fabrication process and external circuit are simple. So far, the filter constructed with this IDT has had a large ripple in the passband due to a large spurious reflection. To alleviate this problem, a new distributed acoustic reflection transducer is proposed as an internal reflection type IDT in which suppression of the unwanted spurious reflection is possible over a broad frequency range. Next, the operation mechanism of this IDT is investigated and a first‐order design method is presented. It is pointed out that a low‐loss filter with an insertion loss less than 10 dB and spurious reflection suppressed by more than 45 dB can be realized with this IDT over a broad frequency range.

A Fully Integrated Filter Circuit for VCRs

In order to miniaturize VCRs, various components have been integrated with semiconductor circuits, but to date video filters such as luminance LPFs, emphasis filters, and chrominance BPFs have not been integrated. We have recently developed an integrated filter circuit for processing video signals. The new circuit was fabricated using a new bipolar process called the Hiplanar process and has been applied to a dynamic emphasis IC for VCRs. Because this filter circuit operates up to 10 MHz, any video filter can be integrated by the same means.

Gyrator video filter IC with automatic tuning

A single-chip gyrator filter for separating the components of the video signal in a TV receiver is described which is suitable for mass production in a standard bipolar process (f/SUB T//spl ap/400 MHz). The 11 mm/SUP 2/ filter chip operates at frequencies up to 10 MHz, requires no tuning or alignment and has Q-factors which are stable with temperature. The IC contains an automatic tuning system which tunes the five resonators of the filter by aligning an auxiliary gyrator resonator with the crystal oscillator present in the color decoder of a TV receiver. Problems of matching the frequencies of the individual gyrator resonators are discussed, showing how alignment accuracy of 0.5 percent can be obtained when resistivities and specific capacitances have production spreads of at least 10 percent. Various gyrator circuit configurations are given which minimize the circuit complexity and, hence, the chip area. Computer aided design techniques for the filter using geometrically scaled models and macromodeling are presented and it is shown how a complete simulation of the chip led to a significant improvement in bandstop performance. Finally, the measured responses are presented and the filter performance is discussed in the light of present-day requirements.

A Second Order Statistical Analysis of the Operation of a Limiter-Phase Detector-Filter Cascade

This paper presents a second-order statistical analysis for the cascade of a bandpass limiter, and ideal phase detector and a video filter. This cascade forms an important subsystem in the mathematical model of some coherent communication systems where information is transmitted by phase or frequency modulation of the carrier. We derive the autocorrelation function R(t <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">1</inf> , t <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> ) of the video filter response when the bandpass limiter input is a fixed amplitude-phase modulated carrier plus stationary gaussian noise. The video filter response is wide sense stationary for some nontrivial cases; these include biphase, single tone, and stationary gaussian noise phase modulation. For these cases, we obtain the video filter output average power spectrum as the Fourier transform of R(τ) for all values of the limiter input signal-to-noise power ratio. An application of the results of this paper is the performance of a FM-PM demodulator for a set of parameters characteristic of one mode of operation of the Apollo Unified S-Band communications system. We present the performance as a family of curves of subcarrier channel output signal-to-noise power ratio as functions of the limiter input signal-to-noise ratio where subcarrier phase modulation index is a parameter. The approach is similar to the analysis by Davenport of the signal-to-noise ratio transfer characteristic of an isolated bandpass limiter.

Attainable Error Probabilities in Demodulation of Random Binary PCM/FM Waveforms

The deviation ratio required for minimum obtainable bit-error probability for random binary PCM/FM waveforms is derived. The resulting minimum obtainable bit-error probabilities are calculated and compared with those obtained expenimentally and independently in two different laboratories using conventional demodulation equipment. The amplitude distribution of video noise in conventional FM receivers is investigated theoretically and experimentally in an attempt to interpret the effect (or lack of effect) of video filtering on error probability. Comparison is also made between theoretically attainable bit-error probabilities for PCM/AM, PCM/PSK, conventional PCM/FM (i.e. frequency modulating a single oscillator) and ``switched PCM/FM'' (i.e. switching between two oscillators of different frequencies).

The Effect of Different Types of Video Filters on PDM-FM and PCM-FM Radio Telemetry

The effects of two limiting types of video filters (namely the ideal low-pass vertical cutoff herein called the ILPF and the Gaussian) on the performance of PDM-FM are compared. It is found that minimum allowable pulse height controls the minimum allowed bandwidth of the Gaussian filter and if crosstalk suppression of 50 to 60 db is required, crosstalk controls the minimum allowed bandwidth of the ILPF. In PCM-FM using the sampling video detector, the critical effect is the overlapping of pulses at sampling time; using the integrating detector, the critical effect is the difference in area under the pulse with adjacent pulses not present and the area with no pulse present but the two adjacent pulses present. In general, the results of the theory agree well with experimental results of Aeronutronic [8] and aid in their interpretation.

Co-Channel Television Interference and its Reduction

The undesired effects of co-channel television interference vary both with the intensity and the frequency of the interfering signal. It is found that there are three types of frequency-variation of objectionability, namely: (1) A progressive decrease of objectionability as the frequency of the undesired signal is shifted away from the carrier frequency of the desired signal, which we have called the Beat Size Effect; (2) superimposed on the Beat Size Effect there is a cyclic variation in objectionability which repeats at intervals corresponding to the horizontal scanning frequency; and (3) superimposed on each of these variations there is a ``finegrain'' cyclic variation which repeats at intervals corresponding to the vertical scanning frequency. We have called the cyclic variation (2) and (3) Beat Pattern Effects. Advantage may be taken of the Beat Size Effect and the Beat Pattern Effects to reduce co-channel television interference by appropriate specification of the operating frequencies and frequency tolerances of the desired and undesired stations. It is shown that it is also possible to reduce the objectionable effects of co-channel television interference by the use of certain post-detection devices in the television receiver. Narrow-band video filters, high-pass video filters, and diode clamp video correction circuits have given promising results.