scholarly journals Single-Band Amplitude Demodulation of Müller-Lyer Illusion Images

2007 ◽  
Vol 10 (1) ◽  
pp. 3-19 ◽  
Author(s):  
Vicente Sierra-Vázquez ◽  
Ignacio Serrano-Pedraza
Keyword(s):  
Spatial Filtering ◽  
Single Band ◽  
Frequency Content ◽  
Visual Model ◽  
Lyer Illusion ◽  
Spatial Frequencies ◽  
Low Pass ◽  
Ill Posed ◽  
Band Pass ◽  
High Pass

The perception of the Müller-Lyer illusion has previously been explained as a result of visual low band-pass spatial filtering, although, in fact, the illusion persists in band-pass and high-pass filtered images without visible low-spatial frequencies. A new theoretical framework suggests that our perceptual experience about the global spatial structure of an image corresponds to the amplitude modulation (AM) component (or its magnitude, also called envelope) of its AM-FM (alternatively, AM-PM) decomposition. Because demodulation is an ill-posed problem with a non-unique solution, two different AM-FM demodulation algorithms were applied here to estimate the envelope of images of Müller-Lyer illusion: the global and exact Daugman and Downing (1995) AMPM algorithm and the local and quasi-invertible Maragos and Bovik (1995) DESA. The images used in our analysis include the classic configuration of illusion in a variety of spatial and spatial frequency content conditions. In all cases, including those of images for which visual low-pass spatial filtering would be ineffective, the envelope estimated by single-band amplitude demodulation has physical distortions in the direction of perceived illusion. It is not plausible that either algorithm could be implemented by the human visual system. It is shown that the proposed second order visual model of pre-attentive segregation of textures (or “back-pocket” model) could recover the image envelope and, thus, explain the perception of this illusion even in Müller-Lyer images lacking low spatial frequencies.

scholarly journals Glass Patterns: Some Contrast Effects Re-Evaluated

Perception ◽  
1997 ◽  
Vol 26 (3) ◽  
pp. 253-268 ◽  
Author(s):  
Steven C Dakin
Keyword(s):  
Spatial Filtering ◽  
Contrast Effects ◽  
Visual Grouping ◽  
Relative Contrast ◽  
Low Pass ◽  
Band Pass ◽  
Opposite Contrast ◽  
Low Pass Filters ◽  
Glass Patterns ◽  
High Pass

The relative contrast of features is known to be important in determining if they can be grouped. Two manipulations of feature contrast have previously been used to criticise models of visual grouping based on spatial filtering: high-pass filtering and reversal of contrast polarity. The effects of these manipulations are considered in the context of the perception of Glass patterns. It is shown that high-pass filtering elements, whilst destroying structure in the output of low-pass filters, do not significantly disrupt the output of locally band-pass filters. The finding that subjects can perceive structure in Glass patterns composed of high-pass features therefore offers no evidence against such spatial filtering mechanisms. Band-pass filtering models are shown to explain the rotation of perceived structure in Glass patterns composed of opposite contrast features. However, structure is correctly perceived in patterns composed of two ‘interleaved’ opposite contrast patterns, which is problematic for oriented filtering mechanisms. Two possible explanations are considered: nonlinear contrast transduction prior to filtering, and integration of local orientation estimates from first-order and second-order mechanisms.

The Importance of High Spatial Frequencies for Exogenous Consciousness. Evidence from the Attentional Blink Paradigm.

2019 ◽  
Author(s):  
Mickaël Jean Rémi Perrier ◽  
Louise Kauffmann ◽  
Carole Peyrin ◽  
Nicolas Vermeulen ◽  
Frederic Dutheil ◽  
...  
Keyword(s):  
Spatial Frequency ◽  
Visual System ◽  
Attentional Blink ◽  
Crucial Role ◽  
Conscious Perception ◽  
Frequency Content ◽  
Spatial Frequencies ◽  
Low Pass ◽  
Visual Consciousness ◽  
High Pass

We attempted to highlight the respective importance of low spatial frequencies (LSFs) and high spatial frequencies (HSFs) in the emergence of visual consciousness by using an attentional blink paradigm in order to manipulate the conscious report of visual stimuli. Thirty-eight participants were asked to identify and report two targets (happy faces) embedded in a rapid stream of distractors (angry faces). Conscious perception of the second target (T2) usually improved as the lag between the targets increased. The distractors between T1 and T2 were either non-filtered (broad spatial frequencies, BSF), low-pass filtered (LSF), or high-pass filtered (HSF). The spatial frequency content of the distractors resulted in a greater disturbance of T2 reporting in the HSF than in the LSF condition. We argue that this could support the idea of HSF information playing a crucial role in the emergence of exogenous consciousness in the visual system. Other interpretations are also discussed.

CURRENT-MODE ACTIVE-C FILTER EMPLOYING REDUCED NUMBER OF CCCII+s

2007 ◽  
Vol 16 (04) ◽  
pp. 507-516 ◽  
Author(s):  
SHAHRAM MINAEI ◽  
ERKAN YUCE
Keyword(s):  
Current Mode ◽  
Pass Band ◽  
Passive Component ◽  
Resistorless Filter ◽  
Low Pass ◽  
Component Matching ◽  
Band Pass ◽  
High Output Impedance ◽  
Quality Factor Q ◽  
High Pass

In this paper, a universal current-mode second-order active-C filter for simultaneously realizing low-pass, band-pass and high-pass responses is proposed. The presented filter employs only three plus-type second-generation current-controlled conveyors (CCCII+s). This filter needs no critical active and passive component matching conditions and no additional active and passive elements for realizing high output impedance low-pass, band-pass and high-pass characteristics. The angular resonance frequency (ω0) and quality factor (Q) of the proposed resistorless filter can be tuned electronically. To verify the theoretical analysis and to exhibit the performance of the proposed filter, it is simulated with SPICE program.

NOVEL VOLTAGE-MODE UNIVERSAL FILTER USING ONLY TWO CDBAs

2005 ◽  
Vol 14 (01) ◽  
pp. 159-164 ◽  
Author(s):  
SUDHANSHU MAHESHWARI ◽  
IQBAL A. KHAN
Keyword(s):  
Pass Band ◽  
Universal Filter ◽  
Input Selection ◽  
Voltage Mode ◽  
Single Output ◽  
Control Computer ◽  
Low Pass ◽  
Band Pass ◽  
Pass Through ◽  
High Pass

A novel voltage-mode universal filter employing only two current differencing buffered amplifiers (CDBAs) is proposed. The filter uses four inputs and single output to realize six responses, viz. low-pass, high-pass, inverting band-pass, noninverting band-pass, band-elimination, and all-pass through input selection with independent pole-Q control. Computer simulation results using SPICE are also given to verify the theory.

scholarly journals Функциональные оптические элементы и устройства терагерцовой фотоники на основе метаповерхностей

2019 ◽  
pp. 84-84
Keyword(s):  
Low Pass ◽  
Band Pass ◽  
High Pass

Освоение диапазона терагерцовых (ТГц) частот электромагнитного спектра (0,1–10 ТГц) делает актуальными задачи разработки и изготовления эффективных оптических элементов для управления характеристиками пучков ТГц-излучения. С инструментальной точки зрения данный спектральный диапазон, соответствующий интервалу длин волн 30÷3000 мкм, удобно позиционирован между примыкающими к нему СВЧ и ИК областями, поскольку позволяет сочетать в терагерцовой аппаратуре инструментальные решения как оптической, так и микроволновой техники. Примером таких решений служат тонкие планарные метало-диэлектрические структуры субволновой топологии, известные в технологии метаматериалов как «метаповерхности» (МП). МП являются, как правило, резонансными электродинамическими структурами, которые эксплуатируются в режиме, когда их характерные резонансные частоты лежат значительно ниже точки возбуждения высших дифракционных гармоник, что отличает такие структуры от дифракционных решеток. Последнее достигается малостью периода расположения элементарных ячеек МП в ее латеральной плоскости в сравнении с рабочей длиной волны. Существенно, что амплитудные, фазовые и поляризационные характеристики МП в заданной полосе частот определяются дизайном ее ячеек, соответствующий выбор которого обеспечивает требуемые функциональные свойства МП-устройств. Последние выгодно сочетают малость толщины/веса и высокую эффективность, которая зачастую не может быть достигнута в рамках решений классической оптики. При этом в ТГц-диапазоне характерный размер элементов топологического рисунка МП в большинстве случаев составляет от нескольких единиц до сотен мкм, что позволяет применять для его производства сравнительно недорогие и хорошо отработанные литографические технологии. В настоящем докладе представлен обзор экспериментальных результатов по разработке оптических элементов и устройств на основе метаповерхностей традиционных и новых конфигураций, которые предназначены как для автономного применения, так и для интеграции с различными метрологическими системами, работающими в области частот от сотни ГГц до нескольких ТГц. Составляя неотъемлемую часть российской элементной базы радиофотоники, разработанные элементы в ряде случаев опережают по функциональным характеристикам отечественные и зарубежные аналоги. Обсуждаются вопросы электродинамического моделирования, технологического производства, спектральной характеризации, а также практического использования следующих типов терагерцовых МП-устройств и систем на их основе: 1) частотные фильтры различных видов: band-pass, low-pass, high-pass; дихроичные мультиплексоры пучков излучения; спектрорадиометрические системы на базе полосовых фильтров; 2) поляризаторы; преобразователи фазы и поляризации; 3) плоские фокусирующие элементы, включая голографические структуры; 4) ультратонкие резонансные поглотители и тепловые детекторы на их основе, включая многоканальные пироэлектрические линейки для спектральных и поляризационных измерений с пространственным разрешением; 5) перестраиваемые ЖК-устройства на основе высокоимпедансных поверхностей; 6) сенсоры тонкопленочных аналитов, включая SEIRA-структуры.

scholarly journals Design and Implementation of Digital Filters for ECG Data Based on Field Programmable Gate Array and MATLAB

2020 ◽  
pp. 17-19
Author(s):  
Emre Cancioglu ◽  
Gokberk Cakiroglu ◽  
Alkim Gokcen ◽  
Yilmaz Sefa Altanay
Keyword(s):  
Digital Filters ◽  
Pass Band ◽  
System Generator ◽  
Design And Implementation ◽  
Field Programmable ◽  
Low Pass ◽  
Band Pass ◽  
Database Platform ◽  
High Pass ◽  
Ecg Data

This study provides design and implementation of four digital filters (low pass, high pass, band pass and band stop) for ECG (electrocardiogram) data on FPGA with MATLAB by a serial communication. The study is conducted with using ECG data which is obtained from PhysioBank Database platform. SysGen (System Generator for DSP) which is a toolbox for MATLAB is used for designing and implementing the digital filters. The aim of the study is to perform four different digital filters with various blocks on the SysGen Toolbox. The study then examines the results of four different digital filters.

A New Tunable SISO Filter Designed in 40nm CMOS for Bilateral Inverse and Buffer Filtering Applications

2021 ◽  
pp. 2150240
Author(s):  
Umar Mohammad ◽  
Fang Tang ◽  
Shu Zhou ◽  
Mohd Yusuf Yasin
Keyword(s):  
Simulation Analysis ◽  
Pass Band ◽  
Single Input Single Output ◽  
Change Of Direction ◽  
Single Output ◽  
Low Pass ◽  
Single Input ◽  
Band Pass ◽  
Parasitic Components ◽  
High Pass

A new study imitating the design and implementation of single-input–single-output (SISO) filters as bilateral filters has been presented in this paper. Second generation current controlled current conveyor (CCCII), being a popular low power active element was considered for the realization of the proposed design. Complete design, analysis and implementation of the voltage mode SISO filter was done using only two CCCII’s and two passive parasitic components. The striking feature of this work is that the proposed design can be made to work at either the input node or the output node, as well as in the cases; the change of direction changes the filter into an inverse filter and buffer filter. Basic filter applications like low-pass, high-pass, band-pass and band-stop were aimed to check the uniformity of the proposed design at different frequencies. Results perceived from the simulation study were fare enough on both the side nodes of the proposed design. Categorically, the circuit can be aimed to work in lieu of a filter transceiver. The consistency of the circuit was analyzed by the nodal analysis. Whereas the working performance was enormously analyzed and evaluated during the simulation analysis. The proposed design was simulated in HSPICE tool to exhibit and exploit the delivery, using the 45[Formula: see text]nm predictive technology model (PTM) parameters, with [Formula: see text][Formula: see text]V rail to rail voltages. Maximum power consumption of the circuit is around 138.5[Formula: see text][Formula: see text]W. Finally, the design was also implemented in Cadence Virtuoso using 40[Formula: see text]nm SMIC parameters.

Effects of high-pass and low-pass spatial filtering on face identification

1996 ◽  
Vol 58 (4) ◽  
pp. 602-612 ◽  
Author(s):  
Nicholas P. Costen ◽  
Denis M. Parker ◽  
Ian Craw
Keyword(s):  
Spatial Filtering ◽  
Face Identification ◽  
Low Pass ◽  
High Pass

scholarly journals Transadmittance Type Universal Current-Mode Biquad Filter Using VDTAs

2014 ◽  
Vol 2014 ◽  
pp. 1-4 ◽  
Author(s):  
Dinesh Prasad ◽  
Mayank Srivastava ◽  
D. R. Bhaskar
Keyword(s):  
Process Parameters ◽  
Current Mode ◽  
Angular Frequency ◽  
Pspice Simulations ◽  
Biquad Filter ◽  
Low Pass ◽  
Single Input ◽  
Band Pass ◽  
Transconductance Amplifiers ◽  
High Pass

A new resistorless single-input-multi-output (SIMO) universal transadmittance (TA) type filter employing two voltage differencing transconductance amplifiers (VDTA) and two grounded capacitors is proposed. The proposed topology realizes simultaneously low pass (LP), high pass (HP), and band pass (BP) filter functions. Band rejects (BR) and all pass (AP) filters are also realizable through appropriate connections of currents. The proposed configuration also offers independent control of natural angular frequency (ω0) and bandwidth (BW) and low active and passive sensitivities. The workability of proposed configuration has been demonstrated through PSPICE simulations with TSMC CMOS 0.18 μm process parameters.

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