Patent•
Method and system for obtaining a first signal for analysis to characterize at least one periodic component thereof
29 Sep 2010-
TL;DR: In this article, the first signal is at least derivable from an output signal obtainable by applying a transformation to the second signals such that any value of the output signal is based on values from each respective second signal at corresponding points in time.
Abstract: A method of facilitating obtaining a first signal, for analysis to characterize at least one periodic component, includes obtaining two second signals representative of intensities of electromagnetic radiation. The first signal is at least derivable from an output signal obtainable by applying a transformation to the second signals such that any value of the output signal is based on values from each respective second signal at corresponding points in time. The method further includes obtaining a value of a variable determining influences of components of respective second signals on the output signal when the signals corresponding to the second signals are captured and the transformation is applied, by (i) analyzing the first, second and/or the output signals to select a value of a parameter corresponding to a respective one of the variables; or (ii) calculating values of at least one time-varying factor corresponding to a respective one of the variables.
Citations
More filters
27 Jun 2016
TL;DR: This work introduces a strategy to dynamically select face regions useful for robust HR estimation, inspired by recent advances on matrix completion theory, which significantly outperforms state-of-the-art HR estimation methods in naturalistic conditions.
Abstract: Recent studies in computer vision have shown that, while practically invisible to a human observer, skin color changes due to blood flow can be captured on face videos and, surprisingly, be used to estimate the heart rate (HR). While considerable progress has been made in the last few years, still many issues remain open. In particular, state of-the-art approaches are not robust enough to operate in natural conditions (e.g. in case of spontaneous movements, facial expressions, or illumination changes). Opposite to previous approaches that estimate the HR by processing all the skin pixels inside a fixed region of interest, we introduce a strategy to dynamically select face regions useful for robust HR estimation. Our approach, inspired by recent advances on matrix completion theory, allows us to predict the HR while simultaneously discover the best regions of the face to be used for estimation. Thorough experimental evaluation conducted on public benchmarks suggests that the proposed approach significantly outperforms state-of the-art HR estimation methods in naturalistic conditions.
280 citations
Patent•
27 Mar 2012TL;DR: In this paper, a method for extracting information from detected characteristic signals was proposed, where a data stream (76, 78, 80, 82) derived from electromagnetic radiation (14) emitted or reflected by an object (11) is received and a plurality of characteristic index elements varying over time can be extracted therefrom.
Abstract: The present invention relates to a device and a method for extracting information from detected characteristic signals. A data stream (76, 78, 80, 82) derivable from electromagnetic radiation (14) emitted or reflected by an object (11) is received and a plurality of characteristic index elements (50) varying over time can be extracted therefrom. The index elements (50) comprise physiological information (48) indicative of at least one at least partially periodic vital signal (12), and a disturbing signal component (58). For eliminating the disturbing signal component (58) to a great extent, the characteristic index elements (50) can be projected to a disturbance-reduced index element (64) having a distinct orientation in relation to a presumed orientation of the disturbing signal component (58). The disturbance-reduced index element (64) is chosen so as to reflect a dominant main orientation and length of the disturbing signal component (58) over time. Consequently, the mainly genuine physiological information (48) extracted from the data stream (76, 78, 80, 82) in this way can be utilized for determining the at least one at least partially periodic vital signal (12).
111 citations
Patent•
16 Aug 2012
TL;DR: In this article, a method of remote monitoring of vital signs by detecting the PPG signal in an image of a subject taken by a video camera such as a webcam was proposed.
Abstract: A method of remote monitoring of vital signs by detecting the PPG signal in an image of a subject taken by a video camera such as a webcam. The PPG signal is identified by auto-regressive analysis of ambient light reflected from a region of interest on the subject's skin. Frequency components of the ambient light and aliasing artefacts resulting from the frame rate of the video camera are cancelled by auto-regressive analysis of ambient light reflected from a region of interest not on the subject's skin, e.g. in the background. This reveals the spectral content of the ambient light allowing identification of the subject's PPG signal. Heart rate, oxygen saturation and breathing rate are obtained from the PPG signal. The values can be combined into a wellness index based on a statistical analysis of the values.
99 citations
Patent•
09 Aug 2010TL;DR: In this paper, a method for remote photoplethysmographic analysis is described, in which a sequence of images from at least one camera is obtained, each represented by pixel data representative of reflected ambient light in at least a limited range of wavelengths.
Abstract: A method of image analysis, includes: obtaining a sequence (37;51) of images, each represented by pixel data; performing a vision-based analysis on at least one of the sequence (37;51) of images to obtain data for classifying a state of a subject represented in the images; - determining at least one value of a physiological parameter of a living being represented in at least some of the sequence (37;51) of images; and classifying a state of the subject using the data obtained with the vision-based analysis and the at least one value of the physiological parameter. The at least one value of the physiological parameter is determined through analysis of image data from the same sequence (37;51) of images from which the at least one image on which the vision-based analysis is performed is taken. A method of enabling remote photoplethysmographic analysis includes: obtaining a sequence (37;51) of images from at least one camera (3), each represented by pixel data representative of reflected ambient light in at least a limited range of wavelengths; and, for at least one measurement zone (41), providing a signal representative of at least variations in a time-varying value of a combination of pixel values at at least a number of image points in the measurement zone (41) for use in determining at least one value of a physiological parameter. At least part of a selected subject represented in the sequence (37;51) of images is tracked, and a directable light source (4) illuminating at least part of the selected subject is controlled.
44 citations
Patent•
24 Aug 2012TL;DR: In this paper, a device and a method for extracting information from detected characteristic signals is presented. But the method is not suitable for the analysis of large-scale data streams, and it cannot be applied to the case where the data stream is composed of a continuous or discrete characteristic signal.
Abstract: The present invention relates to a device and a method for extracting information from detected characteristic signals. A data stream (26; 124a, 124b, 124c) derivable from electromagnetic radiation (14) emitted or reflected by an object (12) is received. The data stream (26) comprises a continuous or discrete characteristic signal (76; 32a, 132b, 132c) including physiological information (100) and a disturbing signal portion 5 (94). The physiological information (100) is representative of at least one at least partially periodic vital signal (20; 156). The disturbing signal portion (94) is representative of at least one of an object motion portion and/or a non-indicative reflection portion. The characteristic signal(76; 132a, 132b, 132c) is transferred by converting at least three absolute components (92a, 92b, 92c) of the characteristic signal (76; 132a, 132b, 132c) related to respective 10 additive channels (74a, 74b, 74c) to at least two difference components (102; 142a, 142b) of the characteristic signal (76; 132a, 132b, 132c), wherein each of the at least two difference components (102; 142a, 142b) can be derived through a respective arithmetic transformation considering at least two of the at least three absolute components (92a, 92b, 92c), wherein the arithmetic transformation comprises additive and subtractive coefficients. Consequently, the 1 disturbing signal portion (94) can beat least partially suppressed in the transferred signal (32; 50).
38 citations
References
More filters
TL;DR: In this paper, a face detection framework that is capable of processing images extremely rapidly while achieving high detection rates is described. But the detection performance is limited to 15 frames per second.
Abstract: This paper describes a face detection framework that is capable of processing images extremely rapidly while achieving high detection rates. There are three key contributions. The first is the introduction of a new image representation called the “Integral Image” which allows the features used by our detector to be computed very quickly. The second is a simple and efficient classifier which is built using the AdaBoost learning algorithm (Freund and Schapire, 1995) to select a small number of critical visual features from a very large set of potential features. The third contribution is a method for combining classifiers in a “cascade” which allows background regions of the image to be quickly discarded while spending more computation on promising face-like regions. A set of experiments in the domain of face detection is presented. The system yields face detection performance comparable to the best previous systems (Sung and Poggio, 1998; Rowley et al., 1998; Schneiderman and Kanade, 2000; Roth et al., 2000). Implemented on a conventional desktop, face detection proceeds at 15 frames per second.
13,037 citations
Book•
01 Jan 1985TL;DR: This chapter discusses Adaptive Arrays and Adaptive Beamforming, as well as other Adaptive Algorithms and Structures, and discusses the Z-Transform in Adaptive Signal Processing.
Abstract: GENERAL INTRODUCTION. Adaptive Systems. The Adaptive Linear Combiner. THEORY OF ADAPTATION WITH STATIONARY SIGNALS. Properties of the Quadratic Performance Surface. Searching the Performance Surface. Gradient Estimation and Its Effects on Adaptation. ADAPTIVE ALGORITHMS AND STRUCTURES. The LMS Algorithm. The Z-Transform in Adaptive Signal Processing. Other Adaptive Algorithms and Structures. Adaptive Lattice Filters. APPLICATIONS. Adaptive Modeling and System Identification. Inverse Adaptive Modeling, Deconvolution, and Equalization. Adaptive Control Systems. Adaptive Interference Cancelling. Introduction to Adaptive Arrays and Adaptive Beamforming. Analysis of Adaptive Beamformers.
5,645 citations
Proceedings Article•
01 Jan 2001TL;DR: Viola et al. as mentioned in this paper proposed a visual object detection framework that is capable of processing images extremely rapidly while achieving high detection rates using a new image representation called the integral image, which allows the features used by the detector to be computed very quickly.
Abstract: This paper describes a visual object detection framework that is capable of processing images extremely rapidly while achieving high detection rates. There are three key contributions. The first is the introduction of a new image representation called the “Integral Image” which allows the features used by our detector to be computed very quickly. The second is a learning algorithm, based on AdaBoost, which selects a small number of critical visual features and yields extremely efficient classifiers [4]. The third contribution is a method for combining classifiers in a “cascade” which allows background regions of the image to be quickly discarded while spending more computation on promising object-like regions. A set of experiments in the domain of face detection are presented. The system yields face detection performance comparable to the best previous systems [16, 11, 14, 10, 1]. Implemented on a conventional desktop, face detection proceeds at 15 frames per second. Author email: fPaul.Viola,Mike.J.Jonesg@compaq.com c Compaq Computer Corporation, 2001 This work may not be copied or reproduced in whole or in part for any commercial purpose. Permission to copy in whole or in part without payment of fee is granted for nonprofit educational and research purposes provided that all such whole or partial copies include the following: a notice that such copying is by permission of the Cambridge Research Laboratory of Compaq Computer Corporation in Cambridge, Massachusetts; an acknowledgment of the authors and individual contributors to the work; and all applicable portions of the copyright notice. Copying, reproducing, or republishing for any other purpose shall require a license with payment of fee to the Cambridge Research Laboratory. All rights reserved. CRL Technical reports are available on the CRL’s web page at http://crl.research.compaq.com. Compaq Computer Corporation Cambridge Research Laboratory One Cambridge Center Cambridge, Massachusetts 02142 USA
1,648 citations
TL;DR: Plethysmographic signals were measured remotely (>1m) using ambient light and a simple consumer level digital camera in movie mode as discussed by the authors, which may be useful for medical purposes such as characterization of vascular skin lesions and remote sensing of vital signs (e.g., heart and respiration rates) for triage or sports purposes.
Abstract: Plethysmographic signals were measured remotely (>1m) using ambient light and a simple consumer level digital camera in movie mode. Heart and respiration rates could be quantified up to several harmonics. Although the green channel featuring the strongest plethysmographic signal, corresponding to an absorption peak by (oxy-) hemoglobin, the red and blue channels also contained plethysmographic information. The results show that ambient light photo-plethysmography may be useful for medical purposes such as characterization of vascular skin lesions (e.g., port wine stains) and remote sensing of vital signs (e.g., heart and respiration rates) for triage or sports purposes.
1,503 citations
TL;DR: A new recursive block-matching motion estimation algorithm with only eight candidate vectors per block is presented and is shown to have a superior performance over alternative algorithms, while its complexity is significantly less.
Abstract: A new recursive block-matching motion estimation algorithm with only eight candidate vectors per block is presented. A fast convergence and a high accuracy, also in the vicinity of discontinuities in the velocity plane, was realized with such new techniques as bidirectional convergence and convergence accelerators. A new search strategy, asynchronous cyclic search, which allows a highly efficient implementation, is presented. A new block erosion postprocessing proposal further effectively eliminates block structures from the generated vector field. Measured with criteria relevant for the field rate conversion application, the new motion estimator is shown to have a superior performance over alternative algorithms, while its complexity is significantly less. >
533 citations