Search results for "Change detection"

CDnet 2014: An Expanded Change Detection Benchmark Dataset

2014

International audience; Change detection is one of the most important low-level tasks in video analytics. In 2012, we introduced the changedetection.net (CDnet) benchmark, a video dataset devoted to the evalaution of change and motion detection approaches. Here, we present the latest release of the CDnet dataset, which includes 22 additional videos (~70,000 pixel-wise annotated frames) spanning 5 new categories that incorporate challenges encountered in many surveillance settings. We describe these categories in detail and provide an overview of the results of more than a dozen methods submitted to the IEEE Change Detection Workshop 2014. We highlight strengths and weaknesses of these metho…

Auditory cortical and hippocampal local-field potentials to frequency deviant tones in urethane-anesthetized rats: An unexpected role of the sound fr…

2015

The human brain can automatically detect auditory changes, as indexed by the mismatch negativity of event-related potentials. The mechanisms that underlie this response are poorly understood. We recorded primary auditory cortical and hippocampal (dentate gyrus, CA1) local-field potentials to serial tones in urethane-anesthetized rats. In an oddball condition, a rare (deviant) tone (p = 0.11) randomly replaced a repeated (standard) tone. The deviant tone was either lower (2200, 2700, 3200, 3700 Hz) or higher (4300, 4800, 5300, 5800 Hz) in frequency than the standard tone (4000 Hz). In an equiprobability control condition, all nine tones were presented at random (p = 0.11). Differential respo…

Multitemporal Unmixing of Medium-Spatial-Resolution Satellite Images: A Case Study Using MERIS Images for Land-Cover Mapping

2011

Data from current medium-spatial-resolution imaging spectroradiometers are used for land-cover mapping and land-cover change detection at regional to global scales. However, few landscapes are homogeneous at these scales, and this creates the so-called mixed-pixel problem. In this context, this study explores the use of the linear spectral mixture model to extract subpixel land-cover composition from medium-spatial-resolution data. In particular, a time series of MEdium Resolution Imaging Spectrometer (MERIS) full-resolution (FR; pixel size of 300 m) images acquired over The Netherlands is used to illustrate this study. The Netherlands was selected because of the following: 1) the fragmenta…

A family of kernel anomaly change detectors

2014

This paper introduces the nonlinear extension of the anomaly change detection algorithms in [1] based on the theory of reproducing kernels. The presented methods generalize their linear counterparts, under both the Gaussian and elliptically-contoured assumptions, and produce both improved detection accuracies and reduced false alarm rates. We study the Gaussianity of the data in Hilbert spaces with kernel dependence estimates, provide low-rank kernel versions to cope with the high computational cost of the methods, and give prescriptions about the selection of the kernel functions and their parameters. We illustrate the performance of the introduced kernel methods in both pervasive and anom…

Modified LACIF filtering in background disjoint noise

2011

Abstract This work deals with pattern recognition methods based on correlations for images in the presence of noise. We propose a modification of the nonlinear Locally Adaptive Contrast Invariant Filter (LACIF) that yields correlation peaks that are invariant to linear intensity changes of the target but that has some limitations in the presence low variance nonoverlapping background noise. The modification of the filter implies a normalization by a global variance of several distributions. The estimation of the variance distributions is done locally by means of correlations. Experimental results as well as comparisons with the classical matched filter and the common LACIF are given.

The scope and limits of implicit visual change detection

2014

Auditory perceptual learning : evidence from electrophysiological recordings in rodents and humans

2018

Yllättävät muutokset äänimaailmassa viestittävät yleensä selviytymisen kannalta tärkeistä vihjeistä, joten niiden nopea ja automaattinen havaitseminen on tärkeää. Tietoinen harjoittelu mahdollistaa havainto-oppimisen ja oppimisen seurauksena hermostoon muodostuu uusia muistijälkiä. Varhaisessa kehityksessä herkkyyskauden aikana muistijälkien muodostuminen, ihmisellä erityisesti puheäänille, on automaattista, eikä siihen vaadita tietoista harjoittelua. Toisaalta perinteisesti on ajateltu, että herkkyyskauden jälkeen vain aktiivinen harjoittelu johtaa uusien muistijälkien muodostumiseen. Muutoksen havaitsemisen hermostollista perustaa voidaan tutkia mittaamalla aivojen sähköisiä jännitevastei…

Shoreline Extraction and Change Detection using 1:5000 Scale Orthophoto Maps: A Case Study of Latvia-Riga

2015

Coastal management requires rapid, up-to-date, and
 correct information. Thus, the determination of coastal movements and its
 directions has primary importance for coastal managers. For monitoring the
 change of shorelines, remote sensing data, very high resolution aerial images
 and orthophoto maps are utilized for detections of change on shorelines. It is
 possible to monitor coastal changes by extracting the coastline from orthophoto
 maps. Along the Baltic Sea and Riga Gulf, Latvian coastline length is 496 km.
 It is rich of coastal resources and natural biodiversity.  Around 120 km of coastline are affected by
 significant coastal chang…

Automatic Processing of Changes in Facial Emotions in Dysphoria: A Magnetoencephalography Study

2018

It is not known to what extent the automatic encoding and change detection of peripherally presented facial emotion is altered in dysphoria. The negative bias in automatic face processing in particular has rarely been studied. We used magnetoencephalography (MEG) to record automatic brain responses to happy and sad faces in dysphoric (Beck’s Depression Inventory ≥ 13) and control participants. Stimuli were presented in a passive oddball condition, which allowed potential negative bias in dysphoria at different stages of face processing (M100, M170, and M300) and alterations of change detection (visual mismatch negativity, vMMN) to be investigated. The magnetic counterpart of the vMMN was el…

Event-related potentials to task-irrelevant changes in facial expressions

2009

Abstract Background Numerous previous experiments have used oddball paradigm to study change detection. This paradigm is applied here to study change detection of facial expressions in a context which demands abstraction of the emotional expression-related facial features among other changing facial features. Methods Event-related potentials (ERPs) were recorded in adult humans engaged in a demanding auditory task. In an oddball paradigm, repeated pictures of faces with a neutral expression ('standard', p = .9) were rarely replaced by pictures with a fearful ('fearful deviant', p = .05) or happy ('happy deviant', p = .05) expression. Importantly, facial identities changed from picture to pi…