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.

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.

Design and feasibility of active matrix flat panel detector using avalanche amorphous selenium for protein crystallography

Abstract: Proteincrystallography is the most important technique for resolving the three-dimensional atomic structure of protein by measuring the intensity of its x-ray diffraction pattern. This work proposes a large area flat panel detector for proteincrystallography based on direct conversion x-ray detection technique using avalanche amorphous selenium ( a - Se ) as the high gain photoconductor, and active matrix readout using amorphous silicon ( a - Si : H ) thin film transistors. The detector employs avalanche multiplication phenomenon of a - Se to make the detector sensitive to each incident x ray. The advantages of the proposed detector over the existing imaging plate and charge coupled device detectors are large area, high dynamic range coupled to single x-ray detection capability, fast readout, high spatial resolution, and inexpensive manufacturing process. The optimal detector design parameters (such as detector size, pixel size, and thickness of a - Se layer), and operating parameters (such as electric field across the a - Se layer) are determined based on the requirements for proteincrystallography application. The performance of the detector is evaluated in terms of readout time ( 1 s ) , dynamic range ( ∼ 10 5 ) , and sensitivity ( ∼ 1 x-rayphoton), thus validating the detector’s efficacy for proteincrystallography.

Digital to analog converter (DAC) having high dynamic range

Abstract: A system having: a digital pre-distortion circuit fed by a digital signal for distorting the digital signal; a digital to analog converter (DAC) core section coupled to an output of the calibration circuit for converting the distorted digital signal into a corresponding analog signal, the DAC core section performing the conversion in accordance with a control signal fed to the DAC core section; a power amplifier (PA) section coupled to an output of the DAC core section for amplifying power in the analog signal; and a calibration circuit coupled to the output of the power amplifier for producing, in response to the power in the power amplified analog signal, the control signal for the DAC core section.

Design of a Tone Mapping Operator for High Dynamic Range Images Based upon Psychophysical Evaluation and Preference Mapping

Abstract: A tone mapping algorithm for displaying high contrast scenes was designed on the basis of the results of experimental tests using human subjects. Systematic perceptual evaluation of several existing tone mapping techniques revealed that the most "natural" appearance was determined by the presence in the output image of detailed scenery features often made visible by limiting contrast and by properly reproducing brightness. Taking these results into account, we developed a system to produce images close to the ideal preference point for high dynamic range input image data. Of the algorithms that we tested, only the Retinex algorithm was capable of retrieving detailed scene features hidden in high luminance areas while still preserving a good contrast level. This paper presents changes made to Retinex algorithm for processing high dynamic range images, and a further integration of the Retinex with specialized tone mapping algorithms that enables the production of images that appear as similar as possible to the viewer's perception of actual scenes.

High-Resolution On-Chip $S$ -Band Radar System Using Stretch Processing

Abstract: In this paper, an $S$ -band radar system that uses stretch processing is developed at the chip level. The novelty in this paper lies in providing an integrated, compact and miniaturized high-performance $S$ -band radar system chipset. The radar has many characteristics that ensure high performance: 1) a wide bandwidth signal (600 MHz) that provides high resolution to distinguish between close objects; 2) an usage of stretch processing, which dramatically reduces the required sampling rates and relaxes the specifications of analog-to-digital converters; 3) high dynamic range (58 dB) that allows weak signals to be detected from targets masked by the high levels of clutter (such as snow and rain); 4) multiple receiver channels that enable digital antenna beamforming at the receiver to mitigate any strong interferer; and 5) operation in the $S$ -band (2–4 GHz) that provides high immunity against clutter in long-range surveillance applications. The architecture study revealed a super-hetrodyne modulator and receiver architecture offered the best solution. The high-order filters were pushed off-chip to reduce silicon area, reduce power consumption, and improve filtering results. The circuit-level design focused on designing the receiver blocks. The design included a high linearity quad passive mixer, IF cascode and common source amplifiers, and a negative-gm voltage controlled oscillator. The total receiver system of the radar chipset was designed and simulated at the circuit level on IBM 180-nm CMOS technology. To the best knowledge of the authors, this is the first integrated and smallest high-performance $S$ -band radar to be designed.