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Showing papers on "High dynamic range published in 2012"


Patent
20 Sep 2012
TL;DR: In this article, a dynamic range transform is applied to the encoded image in response to the display dynamic range indication, which can be used to generate an improved High Dynamic Range image from e.g. a Low Dynamic Range (LDR) image, or vice versa.
Abstract: An image processing apparatus comprises a receiver (201) for receiving an image signal comprising an encoded image. Another receiver (1701) receives a data signal from a display (107) where the data signal comprises a data field that comprises a display dynamic range indication of the display (107). The display dynamic range indication comprises at least one luminance specification for the display. A dynamic range processor (203) is arranged to generate an output image by applying a dynamic range transform to the encoded image in response to the display dynamic range indication. An output (205) outputs an output image signal comprising the output image to the display. The transform may furthermore be performed in response to a target display reference indicative of a dynamic range of display for which the encoded image is encoded. The invention may be used to generate an improved High Dynamic Range (HDR) image from e.g. a Low Dynamic Range (LDR) image, or vice versa.

291 citations


Journal ArticleDOI
TL;DR: It is proved that BLOOMP can reconstruct sparse, widely separated objects up to one Rayleigh length in the Bottleneck distance independent of the grid spacing, and detailed comparisons with the algorithms Spectral Iterative Hard Thresholding (SIHT) and the frame-adapted BP demonstrate the superiority of the BLO-based algorithms for the problem of sparse approximation in terms of highly coherent, redundant dictionaries.
Abstract: Highly coherent sensing matrices arise in discretization of continuum imaging problems such as radar and medical imaging when the grid spacing is below the Rayleigh threshold. Algorithms based on techniques of band exclusion (BE) and local optimization (LO) are proposed to deal with such coherent sensing matrices. These techniques are embedded in the existing compressed sensing algorithms, such as Orthogonal Matching Pursuit (OMP), Subspace Pursuit (SP), Iterative Hard Thresholding (IHT), Basis Pursuit (BP), and Lasso, and result in the modified algorithms BLOOMP, BLOSP, BLOIHT, BP-BLOT, and Lasso-BLOT, respectively. Under appropriate conditions, it is proved that BLOOMP can reconstruct sparse, widely separated objects up to one Rayleigh length in the Bottleneck distance independent of the grid spacing. One of the most distinguishing attributes of BLOOMP is its capability of dealing with large dynamic ranges. The BLO-based algorithms are systematically tested with respect to four performance metrics: dynamic range, noise stability, sparsity, and resolution. With respect to dynamic range and noise stability, BLOOMP is the best performer. With respect to sparsity, BLOOMP is the best performer for high dynamic range, while for dynamic range near unity BP-BLOT and Lasso-BLOT with the optimized regularization parameter have the best performance. In the noiseless case, BP-BLOT has the highest resolving power up to certain dynamic range. The algorithms BLOSP and BLOIHT are good alternatives to BLOOMP and BP/Lasso-BLOT: they are faster than both BLOOMP and BP/Lasso-BLOT and share, to a lesser degree, BLOOMP's amazing attribute with respect to dynamic range. Detailed comparisons with the algorithms Spectral Iterative Hard Thresholding (SIHT) and the frame-adapted BP demonstrate the superiority of the BLO-based algorithms for the problem of sparse approximation in terms of highly coherent, redundant dictionaries.

195 citations


Posted Content
TL;DR: In this paper, a superconducting parametric amplifier was proposed for the microwave frequency superconducted Josephson parametric amplifiers with high dynamic range and low nonlinearity, which can be applied to microwave, millimeter wave and sub-millimeter wave bands.
Abstract: Amplifiers are ubiquitous in electronics and play a fundamental role in a wide range of scientific measurements. From a user's perspective, an ideal amplifier has very low noise, operates over a broad frequency range, and has a high dynamic range - it is capable of handling strong signals with little distortion. Unfortunately, it is difficult to obtain all of these characteristics simultaneously. For example, modern transistor amplifiers offer multi-octave bandwidths and excellent dynamic range. However, their noise remains far above the fundamental limit set by the uncertainty principle of quantum mechanics. Parametric amplifiers, which predate transistor amplifiers and are widely used in optics, exploit a nonlinear response to transfer power from a strong pump tone to a weak signal. If the nonlinearity is purely reactive, ie. nondissipative, in theory the amplifier noise can reach the quantum-mechanical limit. Indeed, microwave frequency superconducting Josephson parametric amplifiers do approach the quantum limit, but generally are narrow band and have very limited dynamic range. In this paper, we describe a superconducting parametric amplifier that overcomes these limitations. The amplifier is very simple, consisting only of a patterned metal film on a dielectric substrate, and relies on the nonlinear kinetic inductance of a superconducting transmission line. We measure gain extending over 2 GHz on either side of an 11.56 GHz pump tone, and we place an upper limit on the added noise of the amplifier of 3.4 photons at 9.4 GHz. Furthermore, the dynamic range is very large, comparable to microwave transistor amplifiers, and the concept can be applied throughout the microwave, millimeter-wave and submillimeter-wave bands.

187 citations


Journal ArticleDOI
TL;DR: A quantum phase estimation algorithm on a single nuclear spin in diamond is implemented to combine both high sensitivity and high dynamic range and achieves a scaling of the precision with time to T(-0.85), which improves the sensitivity and dynamic range.
Abstract: Phase-estimation algorithms applied to single nitrogen nuclear spins in diamond allow weak magnetic fields to be measured with high sensitivity and a large dynamic range.

142 citations


Journal ArticleDOI
TL;DR: In this article, the A-projection algorithm is applied to the Square Kilometer Array (LOFAR) to deal with non-unitary station beams and non-diagonal Mueller matrices.
Abstract: The aimed high sensitivities and large fields of view of the new generation of interferometers impose to reach high dynamic range of order $\sim$1:$10^6$ to 1:$10^8$ in the case of the Square Kilometer Array. The main problem is the calibration and correction of the Direction Dependent Effects (DDE) that can affect the electro-magnetic field (antenna beams, ionosphere, Faraday rotation, etc.). As shown earlier the A-Projection is a fast and accurate algorithm that can potentially correct for any given DDE in the imaging step. With its very wide field of view, low operating frequency ($\sim30-250$ MHz), long baselines, and complex station-dependent beam patterns, the Low Frequency Array (LOFAR) is certainly the most complex SKA precursor. In this paper we present a few implementations of A-Projection applied to LOFAR that can deal with non-unitary station beams and non-diagonal Mueller matrices. The algorithm is designed to correct for all the DDE, including individual antenna, projection of the dipoles on the sky, beam forming and ionospheric effects. We describe a few important algorithmic optimizations related to LOFAR's architecture allowing us to build a fast imager. Based on simulated datasets we show that A-Projection can give dramatic dynamic range improvement for both phased array beams and ionospheric effects. We will use this algorithm for the construction of the deepest extragalactic surveys, comprising hundreds of days of integration.

132 citations


Journal ArticleDOI
TL;DR: An up-to-date review of the recently proposed methods for ghost-free HDR image generation is provided and a classification and comparison of the reviewed methods is reported to serve as a useful guide for future research on this topic.
Abstract: High dynamic range (HDR) image generation and display technologies are becoming increasingly popular in various applications. A standard and commonly used approach to obtain an HDR image is the multiple exposures' fusion technique which consists of combining multiple images of the same scene with varying exposure times. However, if the scene is not static during the sequence acquisition, moving objects manifest themselves as ghosting artefacts in the final HDR image. Detecting and removing ghosting artefacts is an important issue for automatically generating HDR images of dynamic scenes. The aim of this paper is to provide an up-to-date review of the recently proposed methods for ghost-free HDR image generation. Moreover, a classification and comparison of the reviewed methods is reported to serve as a useful guide for future research on this topic.

124 citations


Journal ArticleDOI
TL;DR: The implemented CMOS image sensor using a 0.18-μm technology has the sensitivity of 10-V/lx·s, the conversion gain of 67- μV/e-, and linear digital code range of more than 4 decades.
Abstract: A low temporal noise and high dynamic range CMOS image sensor is developed. A 1Mpixel CMOS image sensor with column-parallel folding-integration and cyclic ADCs has 80μVrms (1.2e-) temporal noise, 82 dB dynamic range using 64 samplings in the folding-integration ADC mode. Very high variable gray-scale resolution of 13b through 19b is attained by changing the number of samplings of pixel outputs. The implemented CMOS image sensor using a 0.18-μm technology has the sensitivity of 10-V/lx·s, the conversion gain of 67- μV/e-, and linear digital code range of more than 4 decades.

108 citations


Journal ArticleDOI
Bo Gu1, Wujing Li1, Jiangtao Wong, Minyun Zhu1, Minghui Wang1 
TL;DR: A novel method for fusing multi-exposure images into a low dynamic range (LDR) image that is suitable for display and visualization but it contains details in the high dynamicrange (HDR) counterpart.

106 citations


Patent
23 Apr 2012
TL;DR: In this article, an image encoding unit (301) arranged to encode a high dynamic range image (IM_HDR-in) comprising: -an LDR selector (311) for identifying a low dynamic range of luminances (R_Norml_LDR) or corresponding range of luma code values within the total range of lumae covered by the high-dynamic range image; -a HDR selector for selecting at least one complementary range (R _ above) within the sum luminae of the two images.
Abstract: To make available a HDR image encoding mechanism with strongly improved usability, we describe an image encoding unit (301) arranged to encode a high dynamic range image (IM_HDR-in) comprising: -an LDR selector (311) for identifying a low dynamic range of luminances (R_Norml_LDR) or corresponding range of luma code values (R_LDR) within the total range of luminances (Range_HDR) covered by the high dynamic range image; -a HDR selector for selecting at least one complementary range (R_above) within the total range of luminances (Range_HDR), comprisingmostly luminances not covered by the low dynamic range of luminances (R_Norml_LDR); -a code mapping unit (315) arranged to encode in a first image (Im_1*), having a luma component comprising N bit code words, pixel luminances of the high dynamic range image (IM_HDR-in) falling within the low dynamic range of luminances (R_Norml_LDR) to code values (Y_out) according to a first mapping (CMAP_L), and pixel luminances of the high dynamic range image (IM_HDR-in) falling within the at least one complementaryrange (R_above) to code values (Y_out) according to a second mapping (CMAP_H), wherein the first and second mappings map to disjunct subranges of the range of luma code values of the first image (RcTot_Im1). Fig. 3

105 citations


Journal ArticleDOI
TL;DR: A microwave camera built upon a two-dimensional array of switchable slot antennas that borrows from modulated scattering techniques to improve isolation among the array elements thus reducing the complexity, cost and size of the array.
Abstract: This paper presents a microwave camera built upon a two-dimensional array of switchable slot antennas. The camera borrows from modulated scattering techniques to improve isolation among the array elements. The camera was designed to measure vector electric field distribution, be compact, portable, battery operated, possess high dynamic range, and be capable of producing real-time images at video frame-rate. This imaging system utilizes PIN diode-loaded resonant elliptical slot antennas as its array elements integrated in a simple and relatively low-loss waveguide network thus reducing the complexity, cost and size of the array. The sensitivity and dynamic range of this system is improved by utilizing a custom-designed heterodyne receiver and matched filter for demodulation. The performance of the multiplexing scheme, noise-floor and dynamic range of the receivers are presented as well. Sources of errors such as mutual-coupling and array response dispersion are also investigated. Finally, utilizing this imaging system for various applications such as 2-D electric field mapping, and nondestructive testing is demonstrated.

104 citations


Patent
13 Aug 2012
TL;DR: In this paper, the authors present a controller for controlling the shutter and the readout circuitry of an electronic camera consisting of a processor and a memory having computer-readable code embodied therein which, when executed by the processor, causes the controller to open the shutter for an image capture period to allow the two or more image sensor arrays to capture pixel data.
Abstract: An electronic camera comprises two or more image sensor arrays. At least one of the image sensor arrays has a high dynamic range. The camera also comprises a shutter for selectively allowing light to reach the two or more image sensor arrays, readout circuitry for selectively reading out pixel data from the image sensor arrays, and, a controller configured to control the shutter and the readout circuitry. The controller comprises a processor and a memory having computer-readable code embodied therein which, when executed by the processor, causes the controller to open the shutter for an image capture period to allow the two or more image sensor arrays to capture pixel data, and, read out pixel data from the two or more image sensor arrays.

Journal ArticleDOI
TL;DR: This paper presents an efficient and accurate multiple exposure fusion technique for the HDRI acquisition, which simultaneously estimates displacements and occlusion and saturation regions by using maximum a posteriori estimation and constructs motion-blur-free HDRIs.
Abstract: A multiple exposure fusion to enhance the dynamic range of an image is proposed The construction of high dynamic range images (HDRIs) is performed by combining multiple images taken with different exposures and estimating the irradiance value for each pixel This is a common process for HDRI acquisition During this process, displacements of the images caused by object movements often yield motion blur and ghosting artifacts To address the problem, this paper presents an efficient and accurate multiple exposure fusion technique for the HDRI acquisition Our method simultaneously estimates displacements and occlusion and saturation regions by using maximum a posteriori estimation and constructs motion-blur-free HDRIs We also propose a new weighting scheme for the multiple image fusion We demonstrate that our HDRI acquisition algorithm is accurate, even for images with large motion

Journal ArticleDOI
TL;DR: Novel phase estimation algorithms are implemented on a single electronic spin associated with the nitrogen-vacancy defect centre in diamond to achieve an ∼8.5-fold improvement in the ratio of the maximum field strength to precision.
Abstract: Phase-estimation algorithms applied to single electronic spins in diamond allow weak magnetic fields to be measured with high sensitivity and a large dynamic range.

Proceedings ArticleDOI
TL;DR: This paper proposes a temporal coherency algorithm that is designed to analyze a video as a whole, and from its characteristics adapts each tone mapped frame of a sequence in order to preserve the temporal co herency.
Abstract: One of the main goals of digital imagery is to improve the capture and the reproduction of real or synthetic scenes on display devices with restricted capabilities. Standard imagery techniques are limited with respect to the dynamic range that they can capture and reproduce. High Dynamic Range (HDR) imagery aims at overcoming these limitations by capturing, representing and displaying the physical value of light measured in a scene. However, current commercial displays will not vanish instantly hence backward compatibility between HDR content and those displays is required. This compatibility is ensured through an operation called tone mapping that retargets the dynamic range of HDR content to the restricted dynamic range of a display device. Although many tone mapping operators exist, they focus mostly on still images. The challenges of tone mapping HDR videos are more complex than those of still images since the temporal dimensions is added. In this work, the focus was on the preservation of temporal coherency when performing video tone mapping. Two main research avenues are investigated: the subjective quality of tone mapped video content and their compression efficiency. Indeed, tone mapping independently each frame of a video sequence leads to temporal artifacts. Those artifacts impair the visual quality of the tone mapped video sequence and need to be reduced. Through experimentations with HDR videos and Tone Mapping Operators (TMOs), we categorized temporal artifacts into six categories. We tested video tone mapping operators (techniques that take into account more than a single frame) on the different types of temporal artifact and we observed that they could handle only three out of the six types. Consequently, we designed a post-processing technique that adapts to any tone mapping operator and reduces the three types of artifact not dealt with. A subjective evaluation reported that our technique always preserves or increases the subjective quality of tone mapped content for the sequences and TMOs tested. The second topic investigated was the compression of tone mapped video content. So far, work on tone mapping and video compression focused on optimizing a tone map curve to achieve high compression ratio. These techniques changed the rendering of the video to reduce its entropy hence removing any artistic intent or constraint on the final results. That is why, we proposed a technique that reduces the entropy of a tone mapped video without altering its rendering.

Journal ArticleDOI
TL;DR: The architecture and API of the Frankencamera are designed and implemented, and two reference implementations are described, which demonstrate several computational photography applications: high dynamic range viewfinding and capture, automated acquisition of extended dynamic range panoramas, foveal imaging, and inertial measurement unit-based hand shake detection.
Abstract: Although there has been much interest in computational photography within the research and photography communities, progress has been hampered by the lack of a portable, programmable camera with sufficient image quality and computing power. To address this problem, we have designed and implemented an open architecture and application programming interface (API) for such cameras: the Frankencamera. It consists of a base hardware specification, a software stack based on Linux, and an API for C++. Our architecture permits control and synchronization of the sensor and image processing pipeline at the microsecond timescale, as well as the ability to incorporate and synchronize external hardware like lenses and flashes. This paper specifies our architecture and API, and it describes two reference implementations we have built. Using these implementations, we demonstrate several computational photography applications: high dynamic range (HDR) viewfinding and capture, automated acquisition of extended dynamic range panoramas, foveal imaging, and inertial measurement unit (IMU)-based hand shake detection. Our goal is to standardize the architecture and distribute Frankencameras to researchers and students, as a step toward creating a community of photographer-programmers who develop algorithms, applications, and hardware for computational cameras.

Proceedings ArticleDOI
01 May 2012
TL;DR: In this paper, the authors used a high-speed digital oscilloscope to measure the actuator power consumption using the Shunt Resistor method and the Monitor Capacitor method in a time-accurate manner.
Abstract: The accurate measurement of power consumption by Dielectric Barrier Discharge (DBD) plasma actuators is a challenge due to the characteristics of the actuator current signal. Micro-discharges generate high-amplitude, high-frequency current spike transients superimposed on a low-amplitude, low-frequency current. We have used a high-speed digital oscilloscope to measure the actuator power consumption using the Shunt Resistor method and the Monitor Capacitor method. The measurements were performed simultaneously and compared to each other in a time-accurate manner. It was found that low signal-to-noise ratios of the oscilloscopes used, in combination with the high dynamic range of the current spikes, make the Shunt Resistor method inaccurate. An innovative, nonlinear signal compression circuit was applied to the actuator current signal and yielded excellent agreement between the two methods. The paper describes the issues and challenges associated with performing accurate power measurements. It provides insights into the two methods including new insight into the Lissajous curve of the Monitor Capacitor method. Extension to a broad range of parameters and further development of the compression hardware will be performed in future work.

Patent
27 Apr 2012
TL;DR: In this article, an apparatus generates an image signal in which pixels are encoded in N-bit words which encode at least a luma per pixel, and a receiver obtains high dynamic range pixel values in accordance with a first color representation in M-bitwords.
Abstract: An apparatus generates an image signal in which pixels are encoded in N-bit words which encode at least a luma per pixel. A receiver (201) obtains high dynamic range pixel values in accordance with a first color representation in M-bitwords. A first generator (203) includes the high dynamic range pixel values in the image signal in the N-bit words according to a second color representation. A second generator (205) includes in the image signal an indicator that high dynamic range pixel values are encoded. In some examples, the high dynamic range pixel values may be provided in a segment that can alternatively contain high or low dynamic range pixel values, and the indicator may indicate which type of data is included. The approach may e.g. facilitate introduction of high dynamic range capability into e.g. HDMI systems.

Journal ArticleDOI
TL;DR: The newly developed experimental and computational platform for assessing tissue transmission spectra is anticipated to have a considerable impact on identifying favorable conditions for laser surgery and optical diagnostics, while providing supplementary information about tissue properties.
Abstract: High dynamic range optical-to-near-infrared transmission measurements for different parts of human body in the spectral range from 650 to 950 nm have been performed. Experimentally measured spectra are correlated with Monte Carlo simulations using chromaticity coordinates in CIE 1976 L*a*b* color space. Both a qualitative and a quantitative agreement have been found, paving a new way of characterizing human tissues in vivo. The newly developed experimental and computational platform for assessing tissue transmission spectra is anticipated to have a considerable impact on identifying favorable conditions for laser surgery and optical diagnostics, while providing supplementary information about tissue properties.

Journal ArticleDOI
TL;DR: In this paper, a charge integrating readout ASIC for silicon strip sensors has been developed at PSI in collaboration with DESY, which is able to cope with the pulsed beam of XFEL machines and at the same time to retain the high dynamic range and single photon resolution performances typical for photon counting systems.
Abstract: A charge integrating readout ASIC (Application Specific Integrated Circuit) for silicon strip sensors has been developed at PSI in collaboration with DESY. The goal of the project is to provide a charge integrating readout system able to cope with the pulsed beam of XFEL machines and at the same time to retain the high dynamic range and single photon resolution performances typical for photon counting systems. The ASIC, designed in IBM 130 nm CMOS technology, takes advantage of its three gain stages with automatic stage selection to achieve a dynamic range of 10000 12 keV photons and a noise better than 300 e.n.c.. The 4 analog outputs of the ASIC are optimized for speed, allowing frame rates higher than 1 MHz, without compromises on linearity and noise performances. This work presents the design features of the ASIC, and reports the characterization results of the chip itself.

Proceedings ArticleDOI
TL;DR: In this article, a software configurable optical test system (SCOTS) based on fringe reflection was implemented for measuring the primary mirror segments of the GMT, using modulated fringe patterns on an LCD monitor as the source, and capturing data with a CCD camera and calibrated imaging optics.
Abstract: A software configurable optical test system (SCOTS) based on fringe reflection was implemented for measuring the primary mirror segments of the Giant Magellan Telescope (GMT). The system uses modulated fringe patterns on an LCD monitor as the source, and captures data with a CCD camera and calibrated imaging optics. The large dynamic range of SCOTS provides good measurement of regions with large slopes that cannot be captured reliably with interferometry. So the principal value of the SCOTS test for GMT is to provide accurate measurements that extend clear to the edge of the glass, even while the figure is in a rough state of figure, where the slopes are still high. Accurate calibration of the geometry and the mapping also enable the SCOTS test to achieve accuracy that is comparable measurement accuracy to the interferometric null test for the small- and middle- spatial scale errors in the GMT mirror.

Patent
01 Nov 2012
TL;DR: In this paper, a base layer and one or more enhancement layers may be used to carry video signals, wherein the base layer cannot be decoded and viewed on its own, and the image data in the enhancement layer video signals may comprise residual values, quantization parameters, and mapping parameters based in part on a prediction method corresponding to a specific method used in the advanced quantization.
Abstract: Techniques use multiple lower bit depth codecs to provide higher bit depth, high dynamic range, images from an upstream device to a downstream device. A base layer and one or more enhancement layers may be used to carry video signals, wherein the base layer cannot be decoded and viewed on its own. Lower bit depth input image data to base layer processing may be generated from higher bit depth high dynamic range input image data via advanced quantization to minimize the volume of image data to be carried by enhancement layer video signals. The image data in the enhancement layer video signals may comprise residual values, quantization parameters, and mapping parameters based in part on a prediction method corresponding to a specific method used in the advanced quantization. Adaptive dynamic range adaptation techniques take into consideration special transition effects, such as fade-in and fade-outs, for improved coding performance.

Journal ArticleDOI
TL;DR: A 1.3-megapixel CMOS image sensor with digital correlated double sampling and 17-b column-parallel two-stage folding-integration/cyclic analog-to-digital converters (ADCs) is developed and is demonstrated at the video rate operation of 30 Hz by the new architecture of the proposed ADCs and the high-performance peripheral logic parts using low-voltage differential signaling circuit.
Abstract: A 1.3-megapixel CMOS image sensor (CIS) with digital correlated double sampling and 17-b column-parallel two-stage folding-integration/cyclic analog-to-digital converters (ADCs) is developed. The image sensor has 0.021-erms- vertical fixed pattern noise, 1.2-erms- pixel temporal noise, and 85.0-dB dynamic range using 32 samplings in the folding-integration ADC mode. Despite the large number of samplings (32 times), the prototype image sensor is demonstrated at the video rate operation of 30 Hz by the new architecture of the proposed ADCs and the high-performance peripheral logic (or digital) parts using low-voltage differential signaling circuit. The developed 17-b CIS has no visible quantization noise at very low light level of 0.01 lx because of high grayscale resolution where 1LSB = 0.1-. The implemented CIS using 0.18- μm technology has the sensitivity of 20 V/lx ·s and the pixel conversion gain of 82 μV/e-.

Journal ArticleDOI
TL;DR: The IDeF-X HD (Imaging Detector Front-end) as mentioned in this paper is a member of the IDeFs-X ASICs family for space applications and is optimized for a half millimeter pitch CdTe or CdZnTe pixelated detector arranged in 16×16 array.
Abstract: Presented circuit, IDeF-X HD (Imaging Detector Front-end) is a member of the IDeF-X ASICs family for space applications. It has been optimized for a half millimeter pitch CdTe or CdZnTe pixelated detector arranged in 16×16 array. It is aimed to operate in the hard X-ray range from few keV up to 250 keV or more. The ASIC has been realized in AMS 0.35 μm CMOS process. The IDeF-X HD is a 32 channel analog front-end with self-triggering capability. The architecture of the analog channel includes a chain of charge sensitive amplifier with continuous reset system and non-stationary noise suppressor, adjustable gain stage, pole-zero cancellation stage, adjustable shaping time low pass filter, baseline holder and peak detector with discriminator. The power consumption of the IDeF-X HD is 800 μW per channel. With the in-channel variable gain stage the nominal 250 keV dynamic range of the ASIC can be extended up to 1 MeV anticipating future applications using thick sensors. Measuring the noise performance without a detector at the input with minimized leakage current (programmable) at the input, we achieved ENC of 33 electrons rms at 10.7 μs peak time. Measurements with CdTe detector show good energy resolution FWHM of 1.1 keV at 60 keV and 4.3 keV at 662 keV with detection threshold below 4 keV. In addition, an absolute temperature sensor has been integrated with resolution of 1.5 °C.

Journal ArticleDOI
TL;DR: In this paper, a pixel-level analog-to-digital conversion (ADC) is implemented at each pixel with a three-transistor structure, where the regenerative latch comparator is divided into an input transistor and the remaining comparator structure shared among the pixels of each column.
Abstract: We present a theoretical analysis, design, and experimental characterization of a CMOS image sensor with pixel-level ΣΔ oversampling analog-to-digital conversion (ADC). The design employs five transistors per-pixel to implement a charge-based ΣΔ ADC at each pixel. In the current design a dynamic regenerative latch comparator is divided into an input transistor, which is contained within each pixel, and the remaining comparator structure shared among the pixels of each column. A charge feedback digital-to-analog converter (DAC) is implemented at each pixel with a three-transistor structure. As opposed to more traditional CMOS image sensors, this image sensor architecture is suitable for implementations in advanced low supply voltage CMOS technologies since its dynamic range is not affected by the reduction of the pixel reset voltage. In addition, similar to the readout methods in low power random access memory designs, this pixel readout architecture does not employ any active amplifiers which allows for low static power operation. Experimental characterization of a prototype fabricated in a 0.35 μm silicided CMOS technology is presented. The estimated power consumption of the fully integrated 128 × 128 imager including decimation filters and I/O interface is 60 nW/pixel at 30 frames per second for 8-bits per-pixel. A peak signal-to-noise ratio of 52 dB and intra-scene dynamic range of 74 dB were measured. The dynamic range was extended to 91 dB through control of the in-pixel DAC supply voltage over the range of 0.8 V-3.3 V.

Patent
Cyrus Bamji1, Swati Mehta1
02 Apr 2012
TL;DR: In this article, the authors provide methods to produce a high performance, feature rich TOF system, phase-based or otherwise using small TOF pixels, single-ended or preferably differential, as well as TOF systems designed.
Abstract: Embodiments of the present invention provide methods to produce a high performance, feature rich TOF system, phase-based or otherwise using small TOF pixels, single-ended or preferably differential, as well as TOF systems so designed. IC chip area required for pixels is reduced by intelligently off-loading or removing from within the pixel certain components and/or functionality. In some embodiments during a single TOF system capture period, analog values from each pixel are repeatedly sampled and converted to digital values, which are combined and manipulated on the sensor chip. Combining this plurality of values enables appropriately compact data from the sensor chip. Embodiments of the present invention implement a TOF system with high ambient light resilience, high dynamic range, low motion blur and dealiasing support, while advantageously reducing pixel area size relative to prior art TOF pixels.

Patent
17 Oct 2012
TL;DR: In this article, the authors presented an improved device provided with a multi-lens and multi-sensor camera module, which has a new mechanism for adjusting multiple lenses and angles of sensors.
Abstract: Disclosed is an improved device provided with a multi-lens and multi-sensor camera module. The device has a new mechanism for adjusting multiple lenses and angles of sensors. The new device makes each lens integrated with perspective of the sensors by using a new principle so that images composited by a multi-lens module have high quality and satisfactory properties such as high resolution, high depth of field, high color saturation, high signal-to-noise ratio, high dynamic range, high sensitivity and the like.

Patent
16 Feb 2012
TL;DR: In this paper, an apparatus and method for generating a high dynamic range (HDR) image from which a ghost blur is removed based on a multi-exposure fusion is presented. But the method is limited to the case of two images.
Abstract: An apparatus and method for generating a High Dynamic Range (HDR) image from which a ghost blur is removed based on a multi-exposure fusion. The apparatus may include an HDR weight map calculation unit to calculate an HDR weight map for multiple exposure frames that are received, a ghost probability calculation unit to calculate a ghost probability for each image by verifying a ghost blur for the multiple exposure frames, an HDR weight map updating unit to update the calculated HDR weight map based on the calculated ghost probability, and a multi-scale blending unit to generate an HDR image by reflecting the updated HDR weight map to the multiple exposure frames.

Proceedings Article
01 Dec 2012
TL;DR: It was confirmed that the proposed methods significantly reduce the bit depth of the enhance layer, even though the compensation slightly increases coding noise.
Abstract: This report proposes two layered bit depth scalable coding methods for high dynamic range (HDR) images expressed in floating point data format. From the base layer bit stream, low dynamic range (LDR) images are decoded. They are tone mapped appropriately for human eye sensitivity, and shortened to a standard bit depth, e.g. 8 [bit]. From the enhance layer bit stream, HDR images are decoded. However the bit depth of this layer has been huge in the existing method. To reduce it, we divide the tone mapping into a reversible logarithmic mapping and its compensation. It was confirmed that the proposed methods significantly reduce the bit depth of the enhance layer, even though the compensation slightly increases coding noise.

Proceedings ArticleDOI
03 Apr 2012
TL;DR: Achieving adequate gain-bandwidth products is nonetheless challenging considering the limited fT of high voltage devices and the availability of an adequate IC technology such as BCD, handling high dynamic range signals at high frequency and capable of multi-watt level driving, opens up to the investigation of integrated amplifier topologies.
Abstract: Transducer drivers for ultrasound imaging are required to have high output power and operation frequency into the MHz range. Furthermore, in harmonic imaging, a well-established method resulting in enhanced contrast, higher harmonic echoes (usually the second) of the fundamental transmitted frequency, either generated by reflection from micro-bubbles or on propagation, are selectively detected and used for imaging [1]. As a consequence, the second harmonic of the transmitted signal is suppressed as much as possible and the received signal is derived solely from the nonlinear behavior of the body. Pulsers are usually adopted having high efficiency, being simple and lending themselves to harmonic imaging for example by means of out-of-phase pulse transmission techniques [1]. Output signals with arbitrary shape allow better performances, enabling apodization profiles with high resolution, beams with low harmonic content and instantaneous changes in transmit energy between pulses [2]. However, the implementation of arbitrary waveform generators in commercial solutions is presently limited to high-end systems because of manufacturing costs, power dissipation and space constraints. To this extent, the availability of an adequate IC technology such as BCD, handling high dynamic range signals at high frequency and capable of multi-watt level driving, opens up to the investigation of integrated amplifier topologies [3]. Advantages in terms of EM interference reduction, reliability improvement, space and cost would derive. Achieving adequate gain-bandwidth products is nonetheless challenging considering the limited f T of high voltage devices.

Journal ArticleDOI
TL;DR: A novel technique, applying multiple-exposure high dynamic range (HDR) imaging to OPT, is presented, and its ability to resolve fine details in zebrafish embryos is demonstrated, without complicated chemical clearing.
Abstract: Traditional optical projection tomography (OPT) acquires a single image at each rotation angle, thereby suffering from limitations in CCD dynamic range; this conventional usage cannot resolve features in samples with highly heterogeneous absorption, such as in small animals with organs of varying size. We present a novel technique, applying multiple-exposure high dynamic range (HDR) imaging to OPT, and demonstrate its ability to resolve fine details in zebrafish embryos, without complicated chemical clearing. We implement the tomographic reconstruction algorithm on the GPU, yielding a performance increase of two orders of magnitude. These features give our method potential application in high-throughput, high-resolution in vivo 3D imaging.