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.

Bottom-up segmentation for ghost-free reconstruction of a dynamic scene from multi-exposure images

Abstract: High Dynamic Range (HDR) imaging requires one to composite multiple differently exposed images of a scene in the irradiance domain and perform tone mapping of the generated HDR image for displaying on Low Dynamic Range (LDR) devices. In the case of dynamic scenes, standard techniques may introduce artifacts called ghosts if the scene changes are not accounted for. In this paper, we consider the HDR problem for dynamic scenes. We develop a novel bottom-up segmentation algorithm through superpixel grouping which would enable us to detect scene changes. We then employ a piecewise patch-based compositing methodology to directly generate the ghost-free LDR image of the dynamic scene. The primary advantage of our approach is that we do not assume any knowledge of camera response function and exposure settings. Further, our approach performs well even in the case of significant scene changes.

High Dynamic Range Variable Fiber-Optical Attenuator Using Digital Micromirrors and Opto-Fluidics

Abstract: To the best of the authors knowledge, proposed is the first variable fiber-optical attenuator (VFOA) using a digital micromirror device (DMD) and an opto-fluidic electronically controlled variable focus lens (ECVFL). The hybrid VFOA uses individually controllable two-state micromirrors of the DMD and the variable focal length capability of the ECVFL to control the amount of light coupled between two fiber ports leading to a high dynamic range VFOA. The demonstrated VFOA at 1545 nm has a 63.5-dB dynamic range, <0.1-dB resolution, 0.2-dB polarization-dependent loss, 4.9-dB optical loss, and < 100-ms switching time. Applications for the proposed VFOA include use in test and measurement systems.

A simple technique for signal compression in high dynamic range, high speed X-ray pixel detectors

Abstract: The availability of high-intensity and high repetition rate X-ray sources, like XFEL facilities, impose severe constraints for the detectors to be developed, in terms of high speed and high dynamic range. For the European XFEL, different detector developments are on the way to readout X-ray flashes with a repetition rate of 4.5MHz with a dynamic range up to 104. In this framework, different compression techniques, at the sensor level or at the electronics readout level, have been adopted to allow the detection system to cope with the required dynamic range, still keeping the noise low enough to provide single photon detection at low signal intensities. In this work, we propose a very simple front-end (FE) solution based on an input PMOS transistor placed on the CMOS readout chip connected to the pixel detector. The FE is optimized for low-noise readout of X-ray photons at low intensities and characterized by a compression of the gain when the signal intensity increases. The PMOSFET is operated in the triode regime and its current is fed into a current-readout filter through a resistor. Larger is the transistor signal, larger is the voltage drop on the resistor which push the transistor to operate more in triode regime at lower gain, producing a compression in the overall FE response. The FE working principle and the first experimental results obtained with a first prototype realized in the 130nm IBM technology are here presented.

Apparatus of high dynamic-range CMOS image sensor and method thereof

Abstract: The present invention discloses an apparatus of high dynamic-range CMOS image sensor and method thereof. The present invention utilize a pixel circuit outputting an output signal, wherein the pixel circuit has a photodiode and a plurality of transistors; and utilize a current source as a charge supplement unit to supply current into one end of the photodiode, and providing charges to the parasitic capacitor of the photodiode to delay saturation in the pixel circuit. In addition, a feedback circuit can be further designed connecting the pixel circuit. The feedback circuit receives the output signal from the pixel circuit and then outputs a control signal according to the output signal of the pixel circuit to control status of the charge supplement unit, and thereby increasing the dynamic range of the CMOS image sensor.

Logarithmic model-based dynamic range enhancement of hip X-ray images

Abstract: Digital capture with consumer digital still camera of the radiographic film significantly decreases the dynamic range and, hence, the details visibility. We propose a method that boosts the dynamic range of the processed X-ray image based on the fusion of a set of digital images acquired under different exposure values. The fusion is controlled by a fuzzy-like confidence information and the luminance range is oversampled by using logarithmic image processing operators.