Showing papers on "High dynamic range published in 2001"

Method for high dynamic range image construction based on multiple images with multiple illumination intensities

Abstract: A method for increasing the dynamic light intensity range of an image by combining pixel data from multiple images collected at different levels of illumination intensity to create a single floating-point image representation of an observed scene.

Motion/saturation detection system and method for synthesizing high dynamic range motion blur free images from multiple captures

Abstract: Motion/Saturation detection system and method for synthesizing high dynamic range motion blur free images from multiple captures, the system and method utilizing photocurrent estimation to reduce read noise and enhance dynamic range at the low illumination end, saturation detection to enhance dynamic range at the high illumination end, and motion blur detection to ensure the photocurrent estimation is not corrupted by motion. Motion blur detection also makes it possible to extend exposure time and to capture more images, which can be used to further enhance dynamic range at the low illumination end. The present invention operates completely locally, making it well suited for single chip digital camera implementations.

Modeling and design of a novel miniaturized integrated optical sensor for gyroscope systems

Abstract: In this paper, we report, for the first time to our knowledge, the modeling and the design of a miniaturized integrated optical sensor, based on a multiple quantum-well (MQW) microring laser, to be used in gyroscope systems. The device can be fully integrated on a single chip and used either in low (e.g., vehicles for land transport) or high (e.g., ships, airplanes, spaceborne platforms) sensitivity navigation systems. The model includes the influence of some physical effects, such as quantum noise, lock in, thermal effect, and sidewall roughness-induced losses. Very good performance has been obtained in terms of gyro quantum limit, operating regions of detectable velocity, thermal range of operation, and power consumption. The proposed architecture shows significant manifold advantages with respect to other existing optical solutions: no polarization-induced noise, no use of frequency-locking techniques, negligible bending losses, high cavity quality factor, complete evaluation of the rotation speed, predictable thermal variation of the gyro scale factor, and very high dynamic range.

High dynamic range panoramic imaging

Abstract: Most imaging sensors have a limited dynamic range and hence can satisfactorily respond to only a part of illumination levels present in a scene. This is particularly disadvantageous for omnidirectional and panoramic cameras since larger fields of view have larger brightness ranges. We propose a simple modification to existing high resolution omnidirectional/panoramic cameras in which the process of increasing the dynamic range is coupled with the process of increasing the field of view. This is achieved by placing a graded transparency (mask) in front of the sensor which allows every scene point to be imaged under multiple exposure settings as the camera pans, a process anyway required to capture large fields of view at high resolution. The sequence of images are then mosaiced to construct a high resolution, high dynamic range panoramic/omnidirectional image. Our method is robust to alignment errors between the mask and the sensor grid and does not require the mask to be placed on the sensing surface. We have designed a panoramic camera with the proposed modifications and have discussed various theoretical and practical issues encountered in obtaining a robust design. We show with an example of high resolution, high dynamic range panoramic image obtained from the camera we designed.

A 1K×1K high dynamic range CMOS image sensor with on-chip programmable region of interest readout

Abstract: An integrated 1024×1024 CMOS image sensor with programmable region of interest (ROI) readout and multi-exposure technique has been developed and successfully tested. Size and position of the ROI is programmed based on multiples of a minimum readout kernel of 32×32 pixels. Since the dynamic range of the irradiance normally exceeds the electrical dynamic range of the imager that can be covered using a single integration time a multi exposure technique has been implemented in the imager. Subsequent sensor images are acquired using different integration times and recomputed to form a single composite image. A newly developed algorithm performing the recomputation is presented. The chip has been realized in a 0.5µm n-well standard CMOS process. The pixel pitch is 10µm × 10µm and the total chip area is 164mm2.

Photocurrent estimation from multiple nondestructive samples in CMOS image sensor

Abstract: CMOS image sensors generally suffer form lower dynamic range than CCDs due to their higher readout noise. Their high speed readout capability and the potential of integrating memory and signal processing with the sensor on the same chip, open up many possibilities for enhancing their dynamic range. Earlier work have demonstrated the use of multiple non-destructive samples to enhance dynamic range, while achieving higher SNR than using other dynamic range enhancement schemes. The high dynamic range image is constructed by appropriately scaling each pixel's last sample before saturation. Conventional CDS is used to reduce offset FPN and reset noise. This simple high dynamic range image construction scheme, however, does not take full advantage of the multiple samples. Readout noise power, which doubles as a result of performing CDS, remain as high as in conventional sensor operation. As a result dynamic range is only extended at the high illumination end. The paper explores the use of linear mean-square-error estimation to more fully exploit the multiple pixel samples to reduce readout noise and thus extend dynamic range at the low illumination end. We present three estimation algorithms: (1) a recursive estimator when reset noise and offset FPN are ignored, (2) a non-recursive algorithm when reset noise and FPN are considered, and (3) a recursive estimation algorithm for case (2), which achieves mean square error close to the non-recursive algorithm without the need to store all the samples. The later recursive algorithm is attractive since it requires the storage of only a few pixel values per pixel, which makes its implementation in a single chip digital imaging system feasible.

Dynamic histogram equalization for high dynamic range images

Abstract: Dynamic range equalization by histogram modification. A histogram is analyzed to determine locations of peaks. A mapping function is formed which relates to the locations of the peaks in a histogram. That mapping function may have areas of highest slope near the peaks. The mapping function is used to form a compressed histogram, which has the required number of levels to display on a display device.

A CMOS log image sensor with on-chip FPN compensation

Abstract: This paper describes a logarithmic image sensor in CMOS technology by using photodiode in photovoltaic mode. Thanks to this pixel design, an electronic dark image reference can be obtained for each pixel readout and a fixed pattern noise (FPN) compensation can be easily done by on-chip analog circuits. A 160×120-pixel prototype circuit in a standard 0.8µn DPDM CMOS technology will be described. This prototype chip has demonstrated low FPN, high dynamic range and high sensitivity at low light condition (<1lux).

High dynamic range, arbitrated address event representation digital imager

Abstract: An 80/spl times/60 pixels arbitrated address-event imager has been designed and fabricated in a 0.6 /spl mu/m CMOS process. The value of the intensity is inversely proportional to the inter-spike interval and the read-out of each spike is initiated by the pixel. The available output bandwidth is allocated according to the pixel's demand, favoring brighter pixels and minimizing power consumption. The imager has a large dynamic range: 200 dB for an individual pixel. The array has a dynamic range of 120 dB. The power consumption is 3.4 mW in uniform indoor light and a mean event rate of 200 kHz (41.7 effective fps). The imager is capable of 8.3 K effective fps.

Split aperture imaging for high dynamic range

Abstract: Most imaging sensors have limited dynamic range and hence are sensitive to only a part of the illumination range present in a natural scene. The dynamic range can be improved by acquiring multiple images of the same scene under different exposure settings and then combining them. In this paper, we describe a camera design for simultaneously acquiring multiple images of the same scene under different exposure settings. The cross-section of the incoming beam from a scene point is partitioned into as many parts as the desired degree of split. This is done by splitting the aperture into multiple parts and directing the light exiting from each in a different direction using an assembly of mirrors. A sensor is placed in the path of each beam and exposure of each sensor is controlled either by appropriately setting its exposure parameter, or by splitting the incoming beam unevenly. The resulting multiple exposure images are used to construct a high dynamic range image. We have implemented a video-rate camera based on this design and the results obtained are presented.

Development of a parallel acquisition system for ultrasound research

Abstract: Medical ultrasound research is typically performed using either video image data, or summed Radio Frequency (RF) data. While such data has led to improved understanding of ultrasound image formation, and in the development of novel image formation and signal processing algorithms, it contains only a fraction of the information available in the individual beamformer channels before summation. This paper describes the development of an advanced experimental system which will simultaneously acquire RF data from 128 individual beamformer channels. We refer to such data, acquired across the transducer face, as aperture domain data. The system will be capable of continuous acquisition over a period of 1.6 seconds, the equivalent of 50 image frames. The system will also incorporate a data interface to allow future connection to custom processing units, ultimately enabling real-time processing of aperture domain data. The system will be constructed around a state of the art Agilent Technologies SONOS 5500 ultrasonic imaging system to enable real-time imaging and preserve broad signal bandwidth, high signal to noise ratio, and high dynamic range. The proposed system will facilitate research on adaptive imaging, system architecture, multidimensional blood flow estimation, broadband transducers, and a number of other areas.

Submicrosecond speed variable optical attenuator using acoustooptics

Abstract: A novel variable optical attenuator (VOA) is introduced that can provide high dynamic range and high-resolution all at fast submicrosecond speeds. The VOA design exploits an in-line one-to-one imaging optical architecture operating with Bragg-mode acoustooptic Bragg cells. Optical attenuation is achieved via frequency and drive voltage control of the Bragg cells, leading to flexible and precise attenuation-level settings. VOA demonstrated a 45-dB dynamic range with a 175-ns switching time. Other measured parameters include 1.14-dB/MHz resolution, 1.56-dB polarization dependent loss, and an excess loss of 3.55 dB.

Experience with SQUID magnetometers in airborne TEM surveying

Abstract: High temperature superconducting quantum interference device (SQUID) magnetometers have been developed in a collaborative project between BHP and CSIRO specifically for application in airborne time domain electromagnetic (TEM) surveying. The objective of this development was to improve the performance of the system in detection of conductors with longer decay time constants, particularly in the presence of a conductive overburden. The sensors were incorporated into a specially designed receiver system and successfully tested as receivers for the GEOTEM system with the assistance of Fugro Airborne Surveys. Their performance was shown to be comparable with, but not superior to current induction coil TEM systems. The development of the receiver system required solutions to a range of problems for the sensor devices and for the receiver system. The principal obstacle for the receiver was in overcoming the high dynamic environment of the towed receiver bird and the consequent high level of noise associated with motion of the sensor in the Earth's magnetic field. The high dynamic range of the magnetometer response, which arises from this motion, was addressed by a combination of modification of the sensor flux-locked loop and periodic resetting of the sensor offset. A digital stacking filter was used to eliminate low-frequency noise associated with motion and a specially designed suspension system was developed to isolate the sensor from higher-frequency motions of the towed bird.

A true logarithmic analog-to-digital pipeline converter with 1.5 bit/stage and digital correction

Abstract: High-resolution pipeline analog-to-digital converters usually employ digital correction techniques to relax the requirements of the flash comparators, thus improving the performance of the converter. This paper exploits the same used common digital techniques to the class of non-linear ADCs, and in the special case of a true logarithmic pipeline converter. While the logarithmic operation is achieved by replacing the linear operations of subtraction and multiplication by simple scaling operations, the use of digital error correction allows to achieve high resolution and high dynamic range. An example is given to illustrate the proposed technique.

Ultra-low power and high dynamic range variable optical attenuator array

Abstract: We present experimental results on an ultra-low drive power 8-channel variable optical attenuator array realized in a highly-integrated planar waveguide platform. The variable optical attenuator (VOA) array features an attenuation range of >25 dB with an applied electrical drive power of only 1.4 mW.

Generating method of high dynamic range image and apparatus therefor, and storage medium for executing program of this method

Abstract: PROBLEM TO BE SOLVED: To provide a method and an apparatus capable of generating an image with high dynamic range at the same frame rate as that of an original image by solving the problem that a frame rate is reduced in half in a conventional technique because an image of one frame is synthesized from images of two frames by a single synthetic algorithm as shown in FIG. (a) 11 in synthesizing an image with high dynamic range from an image sequence in which imaging time is changed into longer and shorter. SOLUTION: As shown in FIGs. (b) 12 and (c) 13, an image with high dynamic range of one frame is formed from an original image of substantial one frame by using two different synthetic algorithms alternately to provide an image with high dynamic range by the same frame rate as that of the original image. In each algorithm, the image of two frames whose imaging times are different are not synthesized as they are, but are synthesized after prediction-forming an image to be obtained at the same imaging time. Thus, unnatural images can be prevented from being synthesized in the case of a motion image.

Direct intermediate frequency sampling wavelet-based analog-to-digital and digital-to-analog converter

Abstract: A direct intermediate frequency sampling analog-to-digital and digital-to-analog converter comprised of (1) a bank of precision analog wavelet generator circuits, (2) synchronization circuits and calibration circuits, and (3) digital measurement circuits. In combination these circuits provide high dynamic range and high sample rate direct intermediate frequency sampling conversion between the discrete-time and continuous-time domains.

Improved high dynamic range switched gain low-noise amplifier for wide-band CDMA applications

Abstract: W-CDMA system require switched gain Low Noise Amplifier (LNA) with wide input dynamic range ICP1 in top of the receiver Front-End. This paper reports the design of an integrated switched gain LNA providing 1.65dB NF at 2140MHz with wide input ICP1=-10dBm in the high gain mode for 15.6 mW power supply. In the low gain mode operation, -11dB power loss is achieve while reducing by two the power consumption. This LNA use the BiCMOS6G SiGe process featuring 0.35µm RF BJT f T >40 GHz and 0.35µm MOS channel length. This process also offer on-chip octogonal inductor with quality factor around 10 at 2Ghz and metal-metal 1fF/µm2capacitor.

Color Filter Array and Color Correction for High Dynamic Range CMOS Image Sensors

Abstract: This contribution presents a novel ap- proach to CMOS color image sensors featuring high dynamic range. First we introduce a novel Color- Filter-Array (CFA) that has been especially de- veloped for CMOS imager featuring high dynamic range. Then color correction method is presented that is made with a fast algorithm realized using a Look-Up-Table (LUT). The LUT is created off-chip to improve a high quality and keep the on-chip logic small.

1.2 V 0.18 &#181;m CMOS imager with column-level oversampling

Abstract: A CMOS imager designed and fabricated in a 0.18 µm digital CMOS technology operating from a 1.2 V power supply is reported. The imager uses second-order oversampled delta-sigma modulator analog to digital conversion at the column level to achieve high dynamic range for this low supply voltage. In experimental tests the imager was shown capable of measuring input light levels ranging over 5 orders of magnitude.

Illumination technique for optical dynamic range compression and offset reduction

Abstract: This paper presents a novel illumination technique for image processing in environments which are characterized by large intensity fluctuations and hence a high optical dynamic range (HDR). This proposal shows how by combining a set of images, flashed with different radiant intensities but with a constant exposure time for the imager, a single image can be produced with a compressed dynamic range and a simultaneously reduced offset. This makes it possible to capture high dynamic range scenes without using a high dynamic range camera. This technique can be used as the first signal processing step to simplify the segmentation in applications such as: face recognition, interior surveillance, vehicle occupant detection or motion detection in general.

Design considerations for high resolution pipeline ADCs in digital CMOS technology

Abstract: The trade-offs between bandwidth, resolution and power in high dynamic range pipeline analog-to-digital converters are studied when a pure digital CMOS technology is considered. Calibration techniques are presented to achieve the required resolution, and the design optimization methodology of the relevant pipeline building blocks are discussed. An example of a 15-bit 10 Ms/s analog-to-digital pipeline converter implemented in a 0.35 /spl mu/m digital CMOS technology is presented.

High dynamic range receiver

Abstract: A multimode receiver/down converter architecture for use with narrow channel bandwidth and channel bandwidth system signals is described. Interfering signals for a selected narrowband channel are attenuated using a method that reduces the dynamic range of the signal for further processing. The proposed method can be used with a receiver architecture, such as Direct-Conversion, low IF, Super heterodyne, and the like. The downconverted signal is split into two paths. One signal path is delayed and subtracted from the signal from the other path. By controlling the delay value, the interference signals at a given offset are attenuated. Based on the chosen architecture, the desired signal is placed so that the signal undergoes minimal distortion.

High-performance SWIR cameras for the telecom industry

Abstract: The need for higher performance short wave length infrared (SWIR) cameras for the telecom industry is becoming increasingly important. This paper will discuss the measured performance and capabilities of Indigo System's near infrared cameras. These cameras are ideally suited for telecom applications because of their high quantum efficiency, uniformity, and linearity over the 1.0 to 1.65 μm wavelength band. The cameras' high dynamic range and high damage threshold to laser light also make them ideally suited for testing and characterizing S-Band, C-band, and L-band fiber optic systems used in DWDM. Measurements of the camera's sensitivity, linearity, uniformity, and dynamic range will be presented and compared to what is currently considered the industry standard, pyroelectric vidicon cameras. The performance improvement resulting from Indigo's approach for reducing the effects of the sensor package window when imaging coherent light will be demonstrated. In addition, an analysis of the camera's tolerance to high levels of laser light will be discussed.

High Dynamic Range CMOS Image Sensors Featuring Multiple Integration and Auto-Calibration

Abstract: Industrial and automotive image acquisition systems require dedicated CMOS image sensors with increased optical dynamic range, high image quality, and a high local contrast. Whereas image sensors with high dynamic range can be realized using logarithmic pixel characteristic their image quality and contrast are rather poor. In this contribution we present image sensors that exhibit high local contrast, high optical dynamic range, and high image quality using linear integrating pixels featuring fast multiple integration. The resulting image is composed of multiple images typically captured at frame rates between 100 and 200 fps. To perform this task in real-time and especially to make it suitable for on-chip implementation dedicated algorithms for image composition from several frames and auto-calibration have been developed and will be presented in this contribution.

Ultraspectral: Hyperspectral and RF Features Registered by IFSAR

Abstract: Hyperspectral remote sensing by air platforms can passively generate over two hundred channels of images of terabyte data the ground surface reflectance/eminence simultaneously, with wavelength ranging from 0.4 to 2.5 µm and to include a full infrared spectrum. We have extended the hyperspectral to include RF spectral for both the foliage penetration (from L band 1 GHz to UHF band 0.5 GHz,) using the polarization RF features and the terrain location ID for automatic navigation registration. These generalizations are possible because we have based our design of the foliage penetration (FOPEN) Interferometric Synthetic Aperture Radar (IFSAR) on all digital transceiver array and Field Programmable Gate Arrays (FPGA). We are able to do that, since we have leveraged the ONR 100 dB Digital Array Radar (DAR) for shipboard volume search radar (VSR) using the matured & rugged GaAs cellular phone technology [1]. We study whether the high dynamic range DAR VSR approach can overcome the long baseline terran curvature (that might otherwise not be suited for the FOLPEN low frequency IFSAR). We show the standard deviation of the phase digital resolution better then 1 o might overcome the terrain curvature due to low frequency, and long time integration. The applications of this technology include environmental monitoring and mineral exploration and mining, communication and Aided Target Recognition (ATR). The hyperspectral imagery takes the advantage of more unique spectral signature in terms of the massively parallel artificial neural network computation using the unsupervised learning Independent Component Analyses (ICA) algorithm introduced to the Landsat by Szu [2, 3] The supervised classification is based on the library of spectral signals of known object material characteristics using various constrained versions of the orthogonal subspace projections (OSP) by [7, 8]. In this paper, we combine both the supervised OSP and the unsupervised ICA hyperspectral imaging algorithms. Then, we present all digital version of FOPEN SAR, considered as one of RF channels in ultraspectral image processing. Taking the advantage of the high dynamic range ONR DAR VSR technology, we can measure both RF signatures and 3D terrain by means of Interferometric (IF) FOPEN SAR. We prefer a real-time one-path fly over using bi-static Interferometric SAR equipped with a Stokes polarization vector information that can provide us with not only the RF signatures but also terrain height for location ID (knowing terran contour map stored in the flight data basis). Such an ultraspectral imaging feature-fusion system can manage Forrest search and rescue when it is complement IFSAR FOPEN with high-resolution EO/IR signatures. Conclusion and discussion are given in the final section.

A "divide and conquer" technique for the design of wide dynamic range continuous time filters

Abstract: This work presents a novel technique for the design of continuous time analog filters with high dynamic range and low power dissipation. The essence of the method is to break up the required dynamic range of the filter in smaller ranges, and utilize separate filters in each one of them. This is done in such a way that the output is not disturbed whenever a different filter takes over. Very serious power dissipation and chip area savings will be shown to result from this technique.

High dynamic range temporal characterization of femtosecond Ti:sapphire oscillators

Abstract: Summary form only given. The main problem limiting today the field of application of multi-terawatts femtosecond lasers in laser-matter experiments is the level of amplified spontaneous emission (ASE) which remains far above the ionization threshold of most materials. Some techniques based on second harmonic generation (SHG) autocorrelation have been developed, but the dynamic is limited to about 8 orders of magnitude and moreover such measurement do not provide any informations on the asymmetry of the pulse shape and do not differentiate the leading and the falling edge. To overpass this problem we have built a high dynamic range third order correlator. As the energy per pulse is small, we added silica lenses in the arms to focus the beams in the non linear crystals (SHG and sum frequency generation (SFG)).