scispace - formally typeset
Search or ask a question
Journal ArticleDOI

Coded aperture imaging with multiple measurements

01 May 1997-Journal of The Optical Society of America A-optics Image Science and Vision (Optical Society of America)-Vol. 14, Iss: 5, pp 1058-1065
TL;DR: In this article, a general theory of coded aperture imaging with multiple measurements is presented, and an image reconstruction scheme from the coded images is described that results in a maximum signal-to-noise ratio.
Abstract: In coded aperture imaging, only aperture arrays consisting of (0, 1) elements are physically realizable. If multiple coded images are obtained with different aperture masks and the resulting detector images are suitably combined, a larger variety of aperture arrays, such as multilevel, complex-valued, vector-valued, or complementary arrays becomes applicable. We present a general theory of coded aperture imaging with multiple measurements. An image reconstruction scheme from the coded images is described that results in a maximum signal-to-noise ratio. Also, the design of sets of aperture arrays is addressed and explicitly solved for several important cases. It is shown how known classes of correlation arrays can be beneficially applied to coded aperture imaging.
Citations
More filters
Patent
29 Mar 2006
TL;DR: In this paper, a system for identifying a human being from movement of the human being is presented, which includes a dual element pyroelectric detector, a Fresnel lens array, and a processor.
Abstract: One embodiment of the present invention is a system for identifying a human being from movement of the human being. The system includes a dual element pyroelectric detector, a Fresnel lens array, and a processor. The dual element pyroelectric detector detects radiation from the human being as the human being moves over time. The Fresnel lens array is located between the dual element pyroelectric detector and the human being. The Fresnel lens array improves collection efficiency and spatial resolution of the dual element pyroelectric detector. The Fresnel lens array includes a mask. The mask provides at least one zone of visibility. The processor is coupled to the dual element pyroelectric detector, the processor converts the detected radiation to a spectral radiation signature. The processor compares the spectral radiation signature to at least a second spectral radiation signature to identify the human being.

226 citations

Journal ArticleDOI
TL;DR: A wireless pyroelectric sensor system, composed of sensing modules (slaves), a synchronization and error rejection module (master), and a data fusion module (host), to perform human tracking and the computation workload distribution among slave, master, and host is investigated.
Abstract: This paper presents a wireless pyroelectric sensor system, composed of sensing modules (slaves), a synchronization and error rejection module (master), and a data fusion module (host), to perform human tracking. The computation workload distribution among slave, master, and host is investigated. The performances and costs of different signal-processing and target-tracking algorithms are discussed. A prototype system is described containing pyroelectric sensor modules that are able to detect the angular displacement of a moving thermal target. Fresnel lens arrays are used to modulate the sensor field of view. The sensor system has been used to track a single human target

177 citations

Journal ArticleDOI
TL;DR: The developed wireless distributed infrared sensor system can run as a standalone prisoner/patient monitoring system under any illumination conditions, as well as a complement for conventional video and audio human tracking and identification systems.
Abstract: This paper presents a wireless distributed pyroelectric sensor system for tracking and identifying multiple humans based on their body heat radiation. This study aims to make pyroelectric sensors a low-cost alternative to infrared video sensors in thermal gait biometric applications. In this system, the sensor field of view (FOV) is specifically modulated with Fresnel lens arrays for functionality of tracking or identification, and the sensor deployment is chosen to facilitate the process of data-object-association. An Expectation-Maximization-Bayesian tracking scheme is proposed and implemented among slave, master, and host modules of a prototype system. Information fusion schemes are developed to improve the system identification performance for both individuals and multiple subjects. The fusion of thermal gait biometric information measured by multiple nodes is tested at four levels: sample, feature, score, and decision. Experimentally, the prototype system is able to simultaneously track two individuals in both follow-up and crossover scenarios with average tracking errors less than 0.5 m. The experimental results also demonstrate system's potential to be a reliable biometric system for the verification/identification of a small group of human subjects. The developed wireless distributed infrared sensor system can run as a standalone prisoner/patient monitoring system under any illumination conditions, as well as a complement for conventional video and audio human tracking and identification systems.

142 citations

Journal ArticleDOI
TL;DR: Known methods as well as several new construction techniques of binary and quadriphase sequences with optimal or best known autocorrelation properties are discussed in this correspondence.
Abstract: Time-discrete signals with good autocorrelation properties are used in various applications in communications engineering. From an implementation point of view, usually sequences with a small phase alphabet and a maximal energy efficiency, i.e., a uniform envelope, are most favorable. For this reason, known methods as well as several new construction techniques of binary and quadriphase sequences with optimal or best known autocorrelation properties are discussed in this correspondence. In many cases, the achievable correlation properties can be improved significantly if a single zero element per sequence is accepted. These "almost" binary and "almost" quadriphase sequences are considered as well. The optimality criteria used include the maximum absolute sidelobe and the merit factor of the periodic and the odd-periodic autocorrelation function, respectively. For sequence lengths of up to 44 in the binary case and up to 32 in the quadriphase case, the best known parameters obtained by computer search are compared with the constructed results.

132 citations

Journal ArticleDOI
TL;DR: This paper uses the abstract notion of light field representation as a general tool to describe computational camera designs, where each camera can be formulated as a projection of a high-dimensional light field to a 2-D image sensor.
Abstract: A computational camera uses a combination of optics and processing to produce images that cannot be captured with traditional cameras. In the last decade, computational imaging has emerged as a vibrant field of research. A wide variety of computational cameras has been demonstrated to encode more useful visual information in the captured images, as compared with conventional cameras. In this paper, we survey computational cameras from two perspectives. First, we present a taxonomy of computational camera designs according to the coding approaches, including object side coding, pupil plane coding, sensor side coding, illumination coding, camera arrays and clusters, and unconventional imaging systems. Second, we use the abstract notion of light field representation as a general tool to describe computational camera designs, where each camera can be formulated as a projection of a high-dimensional light field to a 2-D image sensor. We show how individual optical devices transform light fields and use these transforms to illustrate how different computational camera designs (collections of optical devices) capture and encode useful visual information.

127 citations

References
More filters
PatentDOI
TL;DR: Computer simulations show that the URA with significant shot and background noise is vastly superior to random array techniques without noise, and permits a detector which is smaller than its random array counterpart.
Abstract: A system utilizing uniformly redundant arrays to image non-focusable radiation. The uniformly redundant array is used in conjunction with a balanced correlation technique to provide a system with no artifacts such that virtually limitless signal-to-noise ratio is obtained with high transmission characteristics. Additionally, the array is mosaicked to reduce required detector size over conventional array detectors.

866 citations

Journal ArticleDOI
01 Dec 1976
TL;DR: A simple description of pseudo-random sequences, or maximal-length shift-register sequences, and two-dimensional arrays of area n = 2lm- 1 with the same property.
Abstract: Binary sequences of length n = 2m- 1 whose autocorrelation function is either 1 or -1/n have been known for a long time, and are called pseudo-random (or PN) sequences, or maximal-length shift-register sequences. Two-dimensional arrays of area n = 2lm- 1 with the same property have rcently been found by several authors. This paper gives a simple description of such sequences and arrays and their many nice properties.

774 citations

Journal ArticleDOI
TL;DR: With the addition of MURAs to the family of binary arrays, all prime numbers can now be used for making optimal coded apertures, increasing the number of available square patterns by more than a factor of 3.
Abstract: We introduce a new family of binary arrays for use in coded aperture imaging which are predicted to have properties and sensitivity (SNR) equal to that of the uniformly redundant array (URA). The new arrays, called MURAs (modified URAs), have decoding coefficients all of which are unimodular, resulting in a reconstructed image with noise terms completely independent of image-source structure. Although the new arrays are derived from quadratic residues, they do not belong to the cyclic difference set or set of pseudonoise sequences and consequently are constructible in configurations forbidden to those designs, thus providing the user with a wider selection of aperture patterns to match his particular needs. With the addition of MURAs to the family of binary arrays, all prime numbers can now be used for making optimal coded apertures, increasing the number of available square patterns by more than a factor of 3.

520 citations


"Coded aperture imaging with multipl..." refers background in this paper

  • ...34 With Eq. ( 23 ) we get Eg 5 1/Ea for perfect ternary arrays, and gain 5 F ~1 1 Nj!E...

    [...]

  • ...Eg 5 1 N ( i,j uAi,ju 2, ( 23 ) where Ai,j is the DFT of ai,j....

    [...]

Book
01 Jan 1971
TL;DR: In this paper, the authors discuss the existence questions and constructive existence tests for multipliers and constructiveness tests for difference sets of special type and families of difference sets, and their applications.
Abstract: Existence questions.- Multipliers and constructive existence tests.- Difference sets of special type.- Families of difference sets.- Miscellany.

452 citations

Journal ArticleDOI

437 citations


"Coded aperture imaging with multipl..." refers background in this paper

  • ...i,j ( 2 ) must be the correlational inverse of...

    [...]

  • ...i,j ( 2 ) are found by inserting Eq. (B8) into the constraint Eq. (B2), the result being...

    [...]

  • ...sp,qgp %i,q %j, ( 2 ) where the % signs indicate that the indices must be added modulo Nx or Ny, respectively....

    [...]

  • ...i,j ( 2 ) should be chosen in such a way that they do not both have open elements in any location, since this would increase the transmissions in the denominator of Eq. (26) without increasing the energy Ea in the numerator....

    [...]