Topic
High dynamic range
About: High dynamic range is a research topic. Over the lifetime, 4280 publications have been published within this topic receiving 76293 citations. The topic is also known as: HDR.
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Papers
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24 Jun 1996TL;DR: In this article, a multi-mode SAR radar system in real time by wide bandwidth RF signal generation, precision motion compensation, polar reformatting, autofocusing and high dynamic range image processing is presented.
Abstract: One meter and one foot resolution is achieved in a multi-mode SAR radar system in real time by wide bandwidth RF signal generation, precision motion compensation, polar reformatting, autofocusing and high dynamic range image processing. An exciter/receiver of this system includes means for providing wideband RF waveform generation and down-conversion, while a programmable digital signal processor includes improvements in software for implementing the functions of motion compensation including the presuming of data, polar reformatting, autofocusing and image processing.
58 citations
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01 Apr 2008TL;DR: An optical relay system that allows mechanical or electronic color spectrum control and use it to modify a conventional camera and projector is presented, and applications such as adaptive color primaries, metamer detection, scene contrast enhancement, photographing fluorescent objects, and high dynamic range photography are proposed.
Abstract: We advocate the use of quickly-adjustable, computer-controlled color spectra in photography, lighting and displays. We present an optical relay system that allows mechanical or electronic color spectrum control and use it to modify a conventional camera and projector. We use a diffraction grating to disperse the rays into different colors, and introduce a mask (or LCD/DMD) in the optical path to modulate the spectrum. We analyze the tradeoffs and limitations of this design, and demonstrate its use in a camera, projector and light source. We propose applications such as adaptive color primaries, metamer detection, scene contrast enhancement, photographing fluorescent objects, and high dynamic range photography using spectrum modulation.
58 citations
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29 Jun 2010
TL;DR: In this article, a high dynamic range image is segmented into different regions such that each region is represented by a matrix, where each element of the matrix is a weight or probability of a pixel.
Abstract: A method of tone mapping high dynamic range images for display on low dynamic range displays wherein a high dynamic range image is first accessed. The high dynamic range image is segmented into different regions such that each region is represented by a matrix, where each element of the matrix is a weight or probability of a pixel. An exposure of each region is determined or calculated and the exposure values are applied to the regions responsive to the weight or probability. The different regions are then fused together to obtain a final tone mapped image.
58 citations
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TL;DR: In this paper, the authors present the general detector and ASIC design as well as the results of the prototype characterization measurements for the SwissFEL detector, a 48 × 48 pixel prototype produced in UMC110 nm technology.
Abstract: The SwissFEL, a free electron laser (FEL) based next generation X-ray source, is being built at PSI. An XFEL poses several challenges to the detector development: in particular the single photon counting readout, a successful scheme in case of synchrotron sources, can not be used. At the same time the data quality of photon counting systems, i.e. the low noise and the high dynamic range, is essential from an experimental point of view. Detectors with these features are under development for the EU-XFEL in Hamburg, with the PSI SLS Detector group being involved in one of these efforts (AGIPD). The pulse train time structure of the EU-XFEL machine forces the need of in pixel image storage, resulting in pixel pitches in the 200 μm range. Since the SwissFEL is a 100 Hz repetition rate machine, this constrain is relaxed. For this reason, PSI is developing a 75 μm pitch pixel detector that, thanks to its automatic gain switching technique, will achieve single photon resolution and a high dynamic range. The detector is modular, with each module consisting of a 4 × 8 cm2 active sensor bump bonded to 8 readout ASICs (Application Specific Integrated Circuit), connected to a single printed circuit readout board with 10GbE link capabilities for data download. We have designed and tested a 48 × 48 pixel prototype produced in UMC110 nm technology. In this paper we present the general detector and ASIC design as well as the results of the prototype characterization measurements.
57 citations
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Massachusetts Institute of Technology1, National Radio Astronomy Observatory2, University of Virginia3, Rhodes University4, Harvard University5, Arizona State University6, Australian National University7, Raman Research Institute8, University of Washington9, Victoria University of Wellington10, University of Wisconsin–Milwaukee11, Commonwealth Scientific and Industrial Research Organisation12, Tata Institute of Fundamental Research13, Curtin University14, University of Melbourne15
TL;DR: In this article, the in situ beampattern of the MWA antenna tile relative to that of the reference antenna is measured using power ratio measurements, which cancels the variation of satellite flux or polarization with time.
Abstract: Detection of the fluctuations in a 21 cm line emission from neutral hydrogen during the Epoch of Reionization in thousand hour integrations poses stringent requirements on calibration and image quality, both of which necessitate accurate primary beam models. The Murchison Widefield Array (MWA) uses phased-array antenna elements which maximize collecting area at the cost of complexity. To quantify their performance, we have developed a novel beam measurement system using the 137 MHz ORBCOMM satellite constellation and a reference dipole antenna. Using power ratio measurements, we measure the in situ beampattern of the MWA antenna tile relative to that of the reference antenna, canceling the variation of satellite flux or polarization with time. We employ angular averaging to mitigate multipath effects (ground scattering) and assess environmental systematics with a null experiment in which the MWA tile is replaced with a second-reference dipole. We achieve beam measurements over 30 dB dynamic range in beam sensitivity over a large field of view (65% of the visible sky), far wider and deeper than drift scans through astronomical sources allow. We verify an analytic model of the MWA tile at this frequency within a few percent statistical scatter within the full width at half maximum. Toward the edges of the main lobe and in the sidelobes, we measure tens of percent systematic deviations. We compare these errors with those expected from known beamforming errors.
57 citations