Dynamic range

About: Dynamic range is a research topic. Over the lifetime, 7576 publications have been published within this topic receiving 101739 citations. The topic is also known as: DNR & DR.

Pixel-by-pixel local dimming for high-dynamic-range liquid crystal displays

Abstract: We propose a high dynamic range (HDR) liquid crystal display (LCD) with pixel-level local dimming. The device structure consists of a pixelated LCD dimming panel to control the backlight intensity entering the master LCD panel. According to our analysis and test cell experiment, this dual-panel display system possesses exceedingly high contrast ratio (> 1,000,000:1) and high bit-depth (> 14 bits) at merely 5 volts. Meanwhile, to mitigate the Moire effect induced by the cascaded thin-film transistor (TFT) backplanes, we separate the two LCD panels with a polarization-dependent scattering film. The pros and cons of this HDR display are discussed.

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

Abstract: An integrated 1024/spl times/1024 CMOS image sensor with programmable region-of-interest (ROI) readout and multiexposure 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/spl times/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 multiexposure 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 0.5-/spl mu/m n-well standard CMOS process. The pixel pitch is 10 /spl mu/m/sup 2/ and the total chip area is 164 mm/sup 2/.

Ultrahigh-Resolution Optical Vector Analysis Based on Optical Single-Sideband Modulation

Abstract: Knowing magnitude, phase, and polarization responses is of great importance for fabrication and application of optical devices. A large variety of parameters such as insertion loss, dispersion, group delay, polarization-dependent loss, and polarization mode dispersion can be obtained based on these responses. Conventional approaches achieve the optical spectral responses by sweeping the wavelength of a laser source. Restricted by the low-wavelength accuracy and poor wavelength stability of the wavelength-swept laser source, the resolution of the optical vector analyzers (OVAs) are usually poor (>1.6 pm). To achieve ultrahigh resolution measurement, an OVA based on optical single-sideband (OSSB) modulation has been proposed and developed, which potentially has a sub-Hz resolution. However, electrical-to-optical and optical-to-electrical conversions are required to implement the electrical frequency sweeping and to detect the phase and magnitude information in the electrical domain, which limits the spectral measurement range, accuracy, and dynamic range. In the past decade, great efforts have been devoted to deal with these problems. In this paper, techniques for constructing high-performance OSSB-based OVAs are discussed with an emphasis on the system architectures and operation principles for improving the spectral measurement range, accuracy, and dynamic range of the measurement system. Possible future research directions are also discussed.

Sensor saturation in Fourier multiplexed imaging

Abstract: Optically multiplexed image acquisition techniques have become increasingly popular for encoding different exposures, color channels, light fields, and other properties of light onto two-dimensional image sensors. Recently, Fourier-based multiplexing and reconstruction approaches have been introduced in order to achieve a superior light transmission of the employed modulators and better signal-to-noise characteristics of the reconstructed data. We show in this paper that Fourier-based reconstruction approaches suffer from severe artifacts in the case of sensor saturation, i.e. when the dynamic range of the scene exceeds the capabilities of the image sensor. We analyze the problem, and propose a novel combined optical light modulation and computational reconstruction method that not only suppresses such artifacts, but also allows us to recover a wider dynamic range than existing image-space multiplexing approaches.

Stochastic-flash analog-to-digital conversion

Abstract: Flash-type analog-to-digital converters (ADC's) presenting a nonlinear behavior, i.e., having nonequally spaced threshold levels, may introduce harmonic distortion that can be reduced by employing large-amplitude dither-based conversion techniques. However, large-scale dithering is difficult to implement and, in addition, severely reduces the ADC input dynamic range. In this paper, a new ADC architecture is presented based on ordinary flash conversion and dynamic element matching, that strongly reduces nonlinear distortion. It eliminates the need for large-scale dither signals by randomizing the resistor positions in the resistor string used to generate the voltage references. Some properties of this architecture are analyzed and simulation results that validate the theoretical assumptions are presented.