Showing papers on "High dynamic range published in 2005"

High Dynamic Range Imaging: Acquisition, Display, and Image-Based Lighting (The Morgan Kaufmann Series in Computer Graphics)

Abstract: This landmark book is the first to describe HDRI technology in its entirety and covers a wide-range of topics, from capture devices to tone reproduction and image-based lighting. The techniques described enable you to produce images that have a dynamic range much closer to that found in the real world, leading to an unparalleled visual experience. As both an introduction to the field and an authoritative technical reference, it is essential to anyone working with images, whether in computer graphics, film, video, photography, or lighting design. New material includes chapters on High Dynamic Range Video Encoding, High Dynamic Range Image Encoding, and High Dynammic Range Display Devices Written by the inventors and initial implementors of High Dynamic Range Imaging Covers the basic concepts (including just enough about human vision to explain why HDR images are necessary), image capture, image encoding, file formats, display techniques, tone mapping for lower dynamic range display, and the use of HDR images and calculations in 3D rendering Range and depth of coverage is good for the knowledgeable researcher as well as those who are just starting to learn about High Dynamic Range imaging Table of Contents Introduction; Light and Color; HDR Image Encodings; HDR Video Encodings; HDR Image and Video Capture; Display Devices; The Human Visual System and HDR Tone Mapping; Spatial Tone Reproduction; Frequency Domain and Gradient Domain Tone Reproduction; Inverse Tone Reproduction; Visible Difference Predictors; Image-Based Lighting.

Dynamic range reduction inspired by photoreceptor physiology

Abstract: A common task in computer graphics is the mapping of digital high dynamic range images to low dynamic range display devices such as monitors and printers. This task is similar to the adaptation processes which occur in the human visual system. Physiological evidence suggests that adaptation already occurs in the photoreceptors, leading to a straightforward model that can be easily adapted for tone reproduction. The result is a fast and practical algorithm for general use with intuitive user parameters that control intensity, contrast, and level of chromatic adaptation, respectively.

Compressing and companding high dynamic range images with subband architectures

Abstract: High dynamic range (HDR) imaging is an area of increasing importance, but most display devices still have limited dynamic range (LDR). Various techniques have been proposed for compressing the dynamic range while retaining important visual information. Multi-scale image processing techniques, which are widely used for many image processing tasks, have a reputation of causing halo artifacts when used for range compression. However, we demonstrate that they can work when properly implemented. We use a symmetrical analysis-synthesis filter bank, and apply local gain control to the subbands. We also show that the technique can be adapted for the related problem of "companding", in which an HDR image is converted to an LDR image, and later expanded back to high dynamic range.

Predicting visible differences in high dynamic range images : Model and its calibration

Abstract: New imaging and rendering systems commonly use physically accurate lighting information in the form of high-dynamic range (HDR) images and video. HDR images contain actual colorimetric or physical values, which can span 14 orders of magnitude, instead of 8-bit renderings, found in standard images. The additional precision and quality retained in HDR visual data is necessary to display images on advanced HDR display devices, capable of showing contrast of 50,000:1, as compared to the contrast of 700:1 for LCD displays. With the development of high-dynamic range visual techniques comes a need for an automatic visual quality assessment of the resulting images. In this paper we propose several modifications to the Visual Difference Predicator (VDP). The modifications improve the prediction of perceivable differences in the full visible range of luminance and under the adaptation conditions corresponding to real scene observation. The proposed metric takes into account the aspects of high contrast vision, like scattering of the light in the optics (OTF), nonlinear response to light for the full range of luminance, and local adaptation. To calibrate our HDR VDP we perform experiments using an advanced HDR display, capable of displaying the range of luminance that is close to that found in real scenes.

A perceptual framework for contrast processing of high dynamic range images

Abstract: In this work we propose a framework for image processing in a visual response space, in which contrast values directly correlate with their visibility in an image. Our framework involves a transformation of an image from luminance space to a pyramid of low-pass contrast images and then to the visual response space. After modifying response values, the transformation can be reversed to produce the resulting image. To predict the visibility of suprathreshold contrast, we derive a transducer function for the full range of contrast levels that can be found in High Dynamic Range images. We show that a complex contrast compression operation, which preserves textures of small contrast, is reduced to a linear scaling in the proposed visual response space.

High-dynamic-range still-image encoding in JPEG 2000

Abstract: The raw size of a high-dynamic-range (HDR) image brings about problems in storage and transmission. Many bytes are wasted in data redundancy and perceptually unimportant information. To address this problem, researchers have proposed some preliminary algorithms to compress the data, like RGBE/XYZE, OpenEXR, LogLuv, and so on. HDR images can have a dynamic range of more than four orders of magnitude while conventional 8-bit images retain only two orders of magnitude of the dynamic range. This distinction between an HDR image and a conventional image leads to difficulties in using most existing image compressors. JPEG 2000 supports up to 16-bit integer data, so it can already provide image compression for most HDR images. In this article, we propose a JPEG 2000-based lossy image compression scheme for HDR images of all dynamic ranges. We show how to fit HDR encoding into a JPEG 2000 encoder to meet the HDR encoding requirement. To achieve the goal of minimum error in the logarithm domain, we map the logarithm of each pixel value into integer values and then send the results to a JPEG 2000 encoder. Our approach is basically a wavelet-based HDR still-image encoding method.

Enhancing resolution along multiple imaging dimensions using assorted pixels

Abstract: Multisampled imaging is a general framework for using pixels on an image detector to simultaneously sample multiple dimensions of imaging (space, time, spectrum, brightness, polarization, etc.). The mosaic of red, green, and blue spectral filters found in most solid-state color cameras is one example of multisampled imaging. We briefly describe how multisampling can be used to explore other dimensions of imaging. Once such an image is captured, smooth reconstructions along the individual dimensions can be obtained using standard interpolation algorithms. Typically, this results in a substantial reduction of resolution (and, hence, image quality). One can extract significantly greater resolution in each dimension by noting that the light fields associated with real scenes have enormous redundancies within them, causing different dimensions to be highly correlated. Hence, multisampled images can be better interpolated using local structural models that are learned offline from a diverse set of training images. The specific type of structural models we use are based on polynomial functions of measured image intensities. They are very effective as well as computationally efficient. We demonstrate the benefits of structural interpolation using three specific applications. These are 1) traditional color imaging with a mosaic of color filters, 2) high dynamic range monochrome imaging using a mosaic of exposure filters, and 3) high dynamic range color imaging using a mosaic of overlapping color and exposure filters.

A 2.5-GHz low-power, high dynamic range, self-tuned Q-enhanced LC filter in SOI

Abstract: Q-enhanced LC filter technology offers a promising approach to remove the off-chip preselect filter still required in current transceivers. However, reported designs fail to meet stringent system specifications such as dynamic range and noise figure for existing wireless standards. The complexity and inaccuracy of frequency and Q tuning have also prevented acceptance in industry applications. This paper presents a low-power and high-performance design targeted at Bluetooth in a silicon-on-isolator (SOI) CMOS process. Drawing 5 mA from a 3-V supply, it achieves 23-dB voltage gain (14-dB power gain), approximately 6-dB noise figure, and a 153-dB/spl middot/Hz 1-dB compression point dynamic range, when operating with a 70-MHz bandwidth at 2.5 GHz. A simplified approach to frequency and Q tuning is also demonstrated, making Q-enhanced LC filtering feasible in industry application for the first time.

Perceptually based tone mapping of high dynamic range image streams

Abstract: This paper presents a new perceptually based tone mapping operator that represents scene visibility under timevarying, high dynamic range conditions. The operator is based on a new generalized threshold model that extends the conventional threshold-versus-intensity (TVI) function to account for the viewer's adaptation state, and a new temporal adaptation model that includes fast and slow neural mechanisms as well as photopigment bleaching. These new visual models allow the operator to produce tone-mapped image streams that represent the loss of visibility experienced under changing illumination conditions and in high dynamic range scenes. By varying the psychophysical data that the models use, we simulate the differences in scene visibility experienced by normal and visually impaired observers.

High dynamic range images from low dynamic range images

Abstract: A method for displaying an image includes receiving an image having a first luminance dynamic range and modifying the image to a second luminance dynamic range free from being based upon other images, where the second dynamic range is greater than the first dynamic range. The modified image is displayed on a display.

A translinear RMS detector for embedded test of RF ICs

Abstract: This paper presents a wide-bandwidth, high dynamic range, BiCMOS RF rms detector based on the dynamic translinear principle. A current-domain circuit carries out the main computation, and a circuit compensates for errors due to finite transistor gain. Wide-bandwidth input and output circuits allow connecting voltage-mode signals to the internal current-mode circuitry. Measurements on a prototype chip demonstrate that the circuit is suitable for embedded on-chip testing, particularly for "alternative test" of RF circuits.

Perceptual effects in real-time tone mapping

Abstract: Tremendous progress in the development and accessibility of high dynamic range (HDR) technology that has happened just recently results in fast proliferation of HDR synthetic image sequences and captured HDR video. When properly processed, such HDR data can lead to very convincing and realistic results even when presented on traditional low dynamic range (LDR) display devices. This requires real-time local contrast compression (tone mapping) with simultaneous modeling of important in HDR image perception effects such as visual acuity, glare, day and night vision. We propose a unified model to include all those effects into a common computational framework, which enables an efficient implementation on currently available graphics hardware. We develop a post processing module which can be added as the final stage of any real-time rendering system, game engine, or digital video player, which enhances the realism and believability of displayed image streams.

High dynamic range time-varying integrated receiver for elimination of off-chip filters

Abstract: A quadrature mixer with an LO input is provided. The quadrature mixer receives a signal having a frequency FLO and a signal input having a frequency FSIG and has an output that comprises an output impedance that is high at frequencies of [FLO-FSIG] and [FLO + FSIG] and low at other. A mixer coupled to the output impedance interacts with the output impedance such that an impedance presented at the signal input is high for signals at FSIG if FSIG is a predetermined signal frequency, and low at other frequencies.

DFB fibre-laser sensor developments

Abstract: Distributed feedback (DFB) fibre-laser sensors have been shown to exhibit many characteristics useful in a range of sensing applications. Uniquely, fibre laser sensors enable the wavelength division multiplexing of a number of devices while maintaining the individual sensor characteristics of extremely high strain sensitivity, high dynamic range and very wide measurement bandwidth in small diameter sensors. These factors have led us to investigate a range of applications including hydrophone arrays, accelerometer designs, embedded acoustic emission sensors and acoustic pickups for musical instruments. This paper provides an overview of the optimised DFB sensor performance, interrogation and sensor configurations along with results and a discussion of the future developments of this technology.

Experimental investigation of the nonlinear optical loop mirror with twisted fiber and birefringence bias

Abstract: We examine the transmission characteristics of a NOLM device using a symmetrical coupler, highly twisted fiber, and a quarter-wave (QW) retarder plate introducing a polarization asymmetry in the loop. We demonstrate high dynamic range with controllable transmissivity, and good stability over long times. We experimentally study the transmission behavior for different input polarization states and distinguish between different polarization components of the output beam. Experiments are in good agreement with our theoretical approach previously published. Appropriate choice of the input and output polarizations allows a very high dynamic range. The adjustment of the QW retarder and input polarization enables tuning the critical power over a wide range.

Photometric calibration of high dynamic range cameras

Abstract: The current trends in computer graphics focus on acquiring, processing and reproducing real world scenes, often with a quite high dynamic range (HDR). Many algorithms require such HDR image or video data as an input and the increasing availability of HDR sensors provides a natural source of them. But at the same time the diversity of HDR sensor technology leads to a strong need for photometric calibration of such HDR camera systems in order to retain the fidelity of the final result. We present a calibration approach based on an earlier HDR recovery algorithm for standard low dynamic range (LDR) cameras. We focus here on the specific challenges posed by cameras with a dynamic range of more than six orders of magnitude such as complex camera response curves or selection of appropriate calibration targets. We perform an absolute calibration of two HDR and one LDR camera systems to allow for recovery of real-world luminance values. To validate our approach, we compare these luminance values to measurements performed with a luminance meter for grayscale patches covering a dynamic range of six orders of magnitude. The achieved accuracy of the photometric calibration is sufficient for many measurement and image-based acquisition applications.

Generalized mosaicing: polarization panorama

Abstract: We present an approach to image the polarization state of object points in a wide field of view, while enhancing the radiometric dynamic range of imaging systems by generalizing image mosaicing. The approach is biologically inspired, as it emulates spatially varying polarization sensitivity of some animals. In our method, a spatially varying polarization and attenuation filter is rigidly attached to a camera. As the system moves, it senses each scene point multiple times, each time filtering it through a different filter polarizing angle, polarizance, and transmittance. Polarization is an additional dimension of the generalized mosaicing paradigm, which has recently yielded high dynamic range images and multispectral images in a wide field of view using other kinds of filters. The image acquisition is as easy as in traditional image mosaics. The computational algorithm can easily handle nonideal polarization filters (partial polarizers), variable exposures, and saturation in a single framework. The resulting mosaic represents the polarization state at each scene point. Using data acquired by this method, we demonstrate attenuation and enhancement of specular reflections and semi reflection separation in an image mosaic.

Very high dynamic range and high sampling rate VME digitizing boards for physics experiments

Abstract: The trend in data acquisition systems for modern physics experiments is to digitize analog signals closer and closer to the detector. The digitization systems have followed the progress of commercial analog to digital converters. The state of the art for these devices is currently 225 MSample/s for a 10 to 12 bit range. The new boards, described in this paper, have been designed to improve these performances by an order of magnitude. In its simplest version, this board mainly includes 4 channels sampling analog data up to 2 GSample/s with an analog bandwidth of 300 MHz, and digitizing it with a 12-bit dynamic range. It is based on the custom-designed MATACQ chip. The latter's innovative design permits reaching these performances with power consumption smaller than 1 W. The boards are triggerable either by internal or external signals and several boards are easily synchronizable. The board integrates both GPIB and VME interfaces that permit a maximum readout speed of 500 events/s with the whole memory depth of the 4 channels read

High-dynamic-range VGA with temperature compensation and linear-in-dB gain control

Abstract: This paper presents the design and measured performance of a novel intermediate-frequency variable-gain amplifier for Wideband Code-Division Multiple Access (WCDMA) transmitters. A compensation technique for parasitic coupling is proposed which allows a high dynamic range of 77 dB to be attained at 400 MHz while using a single variable-gain stage. Temperature compensation and decibel-linear characteristic are achieved by means of a control circuit which provides a lower than /spl plusmn/1.5 dB gain error over full temperature and gain ranges. The device is fabricated in a 0.8-/spl mu/m 46 GHz f/sub T/ silicon bipolar technology and drains up to 6 mA from a 2.7-V power supply.

An optimal tone reproduction curve operator for the display of high dynamic range images

Abstract: We present a new tone mapping method for the display of high dynamic range images in low dynamic range devices. We formulate high dynamic range image tone mapping as an optimisation problem. We introduce a two-term cost function, the first term favours linear scaling mapping, the second term favours histogram equalisation mapping, and jointly optimising the two terms optimally maps a high dynamic range image to a low dynamic range image. We control the mapping results by adjusting the relative weightings of the two terms in the objective function. We also present a fast and simple implementation for solving the optimisation problem. We present results to demonstrate that our method works very effectively.

Transfer function and high dynamic range images

Abstract: Methods and apparatuses to derive at least one exposure function for high dynamic range imaging from images of different exposure durations. In one aspect, a method to generate a high dynamic range image from a plurality of images taken with a plurality of exposure durations respectively, includes: computing an exposure function from the plurality of images; and combining the plurality of images into a high dynamic range (HDR) image using the exposure function. In one example of an embodiment, the exposure function is evaluated through: evaluating first data representing a derivative of the exposure function from pixel values of the plurality of images; and integrating the first data to generate second data representing the exposure function.

High Dynamic Range Video Using Split Aperture Camera

Abstract: We present a new approach to display High Dynamic Range (HDR) video using gradient based high dynamic range compression. To obtain HDR video, we utilize the split aperture camera. We apply a spatio-temporal gradient based video integration algorithm for fast and accurate integration of the three input HDR videos into a low dynamic range video, which is suitable for display. The spatiotemporal video integration generates videos with temporal coherency and without artifacts. In order to improve the computational speed, we propose using a diagonal multigrid algorithm to solve the Poisson equation. We show experimental results on a variety of dynamic scenes.

Receiver for a coherent fiber-optic link with high dynamic range and low noise figure

Abstract: Phase modulated coherent fiberoptic links can potentially provide exceptionally high spurious free dynamic range (SFDR) and low noise figure (NF). Critical issue is the development of a strictly linear phase demodulator. In this paper we describe a phase demodulator employing a phase locked loop discriminator. Implementing the PPLL on a single substrate using the state-of-the-art components could yield an SFDR better than 145 dB/Hz2/3 and NF lower than 3dB.

High resolution imaging with Fresnel interferometric arrays: suitability for exoplanet detection

Abstract: We propose a new kind of interferometric array that yields images of high dynamic range and large field. The numerous individual apertures in this array form a pattern related to a Fresnel zone plate. This array can be used for astrophysical imaging over a broad spectral bandwidth spanning from the UV (50 nanometers) to the IR (20 µm). Due to the long focal lengths involved, this instrument requires formation-flying of two space borne vessels. We present the concept and study the S/N ratio in different situations, then apply these results to probe the suitability of this concept to detect exoplanets.

Hybrid analog-digital MEMS fiber-optic variable attenuator

Abstract: To the best of our knowledge, this letter demonstrates the first hybrid analog-digital design fiber-optic variable optical attenuator (VOA) that can simultaneously provide high dynamic range as well as super resolution attenuation controls. The demonstrated VOA shows an 81-dB controlled dynamic range, a <0.1-dB resolution, a 2.25-dB optical loss, a <0.05-dB polarization-dependant loss, and C-band operations. The VOA is suited for optical test and instrument applications.

Efficient charge transferring in CMOS imagers

Abstract: Methods for operating a pixel cell include efficient transferring of photo-charges using multiple pulses to a transistor transfer gate during a charge integration period for an associated photosensor. The pixel cell can be operated with efficient transfer characteristics in either normal or high dynamic range (HDR) mode. The high dynamic range can be realized by either operating an optional HDR transistor or by fluctuating the voltage applied to a reset gate.

Perceptual Effects in Real-Time Tone Mapping

Abstract: Tremendous progress in the development and accessibility of high dynamic range (HDR) technology that has happened just recently results in fast proliferation of HDR synthetic image sequences and captured HDR video. When properly processed, such HDR data can lead to very convincing and realistic results even when presented on traditional low dynamic range (LDR) display devices. This requires real-time local contrast compression (tone mapping) with simultaneous modeling of important in HDR image perception effects such as visual acuity, glare, day and night vision. We propose a unified model to include all those effects into a common computational framework, which enables an efficient implementation on currently available graphics hardware. We develop a post processing module which can be added as the final stage of any real-time rendering system, game engine, or digital video player, which enhances the realism and believability of displayed image streams.

System for high dynamic range analysis in flow cytometry

Abstract: A flow cytometer (700) capable of using electronics (7, 9) to analyze a large dynamic range while avoiding and/or correcting traditional limitations of acquisition electronics. The invention allows for measuring signal characteristics, which may include but are not limited to linear peak, integral, logarithmic peak, and pulse width. Other system parameters may also be generated by the invention to indicate timing or status information. Accurate and precise measurements may be performed by correcting for input errors if needed, and by transforming the input signal (1) to produce a more easily measured form.

High-dynamic-range ultra wide band transceiver

Abstract: An UWB Transceiver for Multi-Band OFDM communication including an antenna switch ( 342 ), a receive front end and down-converter ( 303 ), an up-converter and power amplifier ( 305 ), and a frequency synthesizer ( 211 ). The transceiver achieves high dynamic range by employing a synthesizer ( 211 ) with very low spurious components and a receive front end with an efficient receive RF filtering embodiment. The synthesizer ( 211 ) may rapidly switch frequencies in a manner that minimizes spurious components outside the band group used for communication. The receiver ( 200 ) also achieves high selectivity and sensitivity by dividing the receive signal path into even and odd band groups.