Showing papers on "High dynamic range published in 2011"

The image processing handbook

Abstract: "This guide clearly explains the acquisition and use of digital images in a wide variety of scientific fields. This sixth edition features new sections on selecting a camera with resolution appropriate for use on light microscopes, on the ability of current cameras to capture raw images with high dynamic range, and on imaging in more than two dimensions. It discusses Dmax for X-ray images and combining images with different exposure settings to further extend the dynamic range. This edition also includes a new chapter on shape measurements, a review of new developments in image file searching, and a wide range of new examples and diagrams"

A QVGA 143 dB Dynamic Range Frame-Free PWM Image Sensor With Lossless Pixel-Level Video Compression and Time-Domain CDS

Abstract: The biomimetic CMOS dynamic vision and image sensor described in this paper is based on a QVGA (304×240) array of fully autonomous pixels containing event-based change detection and pulse-width-modulation (PWM) imaging circuitry. Exposure measurements are initiated and carried out locally by the individual pixel that has detected a change of brightness in its field-of-view. Pixels do not rely on external timing signals and independently and asynchronously request access to an (asynchronous arbitrated) output channel when they have new grayscale values to communicate. Pixels that are not stimulated visually do not produce output. The visual information acquired from the scene, temporal contrast and grayscale data, are communicated in the form of asynchronous address-events (AER), with the grayscale values being encoded in inter-event intervals. The pixel-autonomous and massively parallel operation ideally results in lossless video compression through complete temporal redundancy suppression at the pixel level. Compression factors depend on scene activity and peak at ~1000 for static scenes. Due to the time-based encoding of the illumination information, very high dynamic range - intra-scene DR of 143 dB static and 125 dB at 30 fps equivalent temporal resolution - is achieved. A novel time-domain correlated double sampling (TCDS) method yields array FPN of 56 dB (9.3 bit) for >10 Lx illuminance.

Hdr-vdp-2

Abstract: Visual metrics can play an important role in the evaluation of novel lighting, rendering, and imaging algorithms. Unfortunately, current metrics only work well for narrow intensity ranges, and do n...

Advanced High Dynamic Range Imaging: Theory and Practice

Abstract: Imaging techniques seek to simulate the array of light that reaches our eyes to provide the illusion of sensing scenes directly. Both photography and computer graphics deal with the generation of images. Both disciplines have to cope with the high dynamic range in the energy of visible light that human eyes can sense. Traditionally photography and computer graphics took different approaches to the high dynamic range problem. Work over the last ten years though has unified these disciplines and created powerful new tools for the creation of complex, compelling and realistic images. This book provides a practical introduction to the emerging new discipline of high dynamic range imaging that combines photography and computer graphics. By providing detailed equations and code, the book gives the reader the tools needed to experiment with new techniques for creating compelling images. A supplemental website contains downloads and additional information.

Layered 3D: tomographic image synthesis for attenuation-based light field and high dynamic range displays

Abstract: We develop tomographic techniques for image synthesis on displays composed of compact volumes of light-attenuating material. Such volumetric attenuators recreate a 4D light field or high-contrast 2D image when illuminated by a uniform backlight. Since arbitrary oblique views may be inconsistent with any single attenuator, iterative tomographic reconstruction minimizes the difference between the emitted and target light fields, subject to physical constraints on attenuation. As multi-layer generalizations of conventional parallax barriers, such displays are shown, both by theory and experiment, to exceed the performance of existing dual-layer architectures. For 3D display, spatial resolution, depth of field, and brightness are increased, compared to parallax barriers. For a plane at a fixed depth, our optimization also allows optimal construction of high dynamic range displays, confirming existing heuristics and providing the first extension to multiple, disjoint layers. We conclude by demonstrating the benefits and limitations of attenuation-based light field displays using an inexpensive fabrication method: separating multiple printed transparencies with acrylic sheets.

Optimizing a Tone Curve for Backward-Compatible High Dynamic Range Image and Video Compression

Abstract: For backward compatible high dynamic range (HDR) video compression, the HDR sequence is reconstructed by inverse tone-mapping a compressed low dynamic range (LDR) version of the original HDR content. In this paper, we show that the appropriate choice of a tone-mapping operator (TMO) can significantly improve the reconstructed HDR quality. We develop a statistical model that approximates the distortion resulting from the combined processes of tone-mapping and compression. Using this model, we formulate a numerical optimization problem to find the tone-curve that minimizes the expected mean square error (MSE) in the reconstructed HDR sequence. We also develop a simplified model that reduces the computational complexity of the optimization problem to a closed-form solution. Performance evaluations show that the proposed methods provide superior performance in terms of HDR MSE and SSIM compared to existing tone-mapping schemes. It is also shown that the LDR image quality resulting from the proposed methods matches that produced by perceptually-based TMOs.

Compatible compression of high dynamic range, visual dynamic range, and wide color gamut video

Abstract: A first image stream has a first dynamic range and a first color space. First and the second image streams are received in a layered codec. The second image stream has a second dynamic range, which is higher than the first dynamic range. The first image stream is in the codec's base layer; the second image stream is in its enhancement layer. The first image stream is encoded to obtain an encoded image stream, which is decoded to obtain a decoded image stream. The decoded image stream is converted from the first non-linear or linear color space to a second, different color space to obtain a color converted image stream. A higher dynamic range image representation of the color converted image stream is generated to obtain a transformed image stream. Inverse tone mapping parameters are generated based on the transformed image stream and the second image stream.

Coherence-Pattern Guided Compressive Sensing with Unresolved Grids

Abstract: Highly coherent sensing matrices arise in discretization of continuum imaging problems such as radar and medical imaging when the grid spacing is below the Rayleigh threshold. Algorithms based on techniques of band exclusion (BE) and local optimization (LO) are proposed to deal with such coherent sensing matrices. These techniques are embedded in the existing compressed sensing algorithms such as Orthogonal Matching Pursuit (OMP), Subspace Pursuit (SP), Iterative Hard Thresholding (IHT), Basis Pursuit (BP) and Lasso, and result in the modified algorithms BLOOMP, BLOSP, BLOIHT, BP-BLOT and Lasso-BLOT, respectively. Under appropriate conditions, it is proved that BLOOMP can reconstruct sparse, widely separated objects up to one Rayleigh length in the Bottleneck distance {\em independent} of the grid spacing. One of the most distinguishing attributes of BLOOMP is its capability of dealing with large dynamic ranges. The BLO-based algorithms are systematically tested with respect to four performance metrics: dynamic range, noise stability, sparsity and resolution. With respect to dynamic range and noise stability, BLOOMP is the best performer. With respect to sparsity, BLOOMP is the best performer for high dynamic range while for dynamic range near unity BP-BLOT and Lasso-BLOT with the optimized regularization parameter have the best performance. In the noiseless case, BP-BLOT has the highest resolving power up to certain dynamic range. The algorithms BLOSP and BLOIHT are good alternatives to BLOOMP and BP/Lasso-BLOT: they are faster than both BLOOMP and BP/Lasso-BLOT and shares, to a lesser degree, BLOOMP's amazing attribute with respect to dynamic range. Detailed comparisons with existing algorithms such as Spectral Iterative Hard Thresholding (SIHT) and the frame-adapted BP are given.

Theoretical Design and Analysis of Multivolume Digital Assays with Wide Dynamic Range Validated Experimentally with Microfluidic Digital PCR

Abstract: This paper presents a protocol using theoretical methods and free software to design and analyze multivolume digital PCR (MV digital PCR) devices; the theory and software are also applicable to design and analysis of dilution series in digital PCR. MV digital PCR minimizes the total number of wells required for “digital” (single molecule) measurements while maintaining high dynamic range and high resolution. In some examples, multivolume designs with fewer than 200 total wells are predicted to provide dynamic range with 5-fold resolution similar to that of single-volume designs requiring 12 000 wells. Mathematical techniques were utilized and expanded to maximize the information obtained from each experiment and to quantify performance of devices and were experimentally validated using the SlipChip platform. MV digital PCR was demonstrated to perform reliably, and results from wells of different volumes agreed with one another. No artifacts due to different surface-to-volume ratios were observed, and single molecule amplification in volumes ranging from 1 to 125 nL was self-consistent. The device presented here was designed to meet the testing requirements for measuring clinically relevant levels of HIV viral load at the point-of-care (in plasma, 1 000 000 molecules/mL), and the predicted resolution and dynamic range was experimentally validated using a control sequence of DNA. This approach simplifies digital PCR experiments, saves space, and thus enables multiplexing using separate areas for each sample on one chip, and facilitates the development of new high-performance diagnostic tools for resource-limited applications. The theory and software presented here are general and are applicable to designing and analyzing other digital analytical platforms including digital immunoassays and digital bacterial analysis. It is not limited to SlipChip and could also be useful for the design of systems on platforms including valve-based and droplet-based platforms. In a separate publication by Shen et al. (J. Am. Chem. Soc., 2011, DOI: 10.1021/ja2060116), this approach is used to design and test digital RT-PCR devices for quantifying RNA.

High dynamic range image generation and rendering

Abstract: Techniques and tools for high dynamic range (HDR) image rendering and generation. An HDR image generating system performs motion analysis on a set of lower dynamic range (LDR) images and derives relative exposure levels for the images based on information obtained in the motion analysis. These relative exposure levels are used when integrating the LDR images to form an HDR image. An HDR image rendering system tone maps sample values in an HDR image to a respective lower dynamic range value, and calculates local contrast values. Residual signals are derived based on local contrast, and sample values for an LDR image are calculated based on the tone-mapped sample values and the residual signals. User preference information can be used during various stages of HDR image generation or rendering.

Development of the DEPFET sensor with signal compression: A large format X-ray imager with mega-frame readout capability for the European XFEL

Abstract: We present the development of the DSSC instrument: an ultra-high speed detector system for the new European XFEL in Hamburg. The DSSC will be able to record X-ray images with a maximum frame rate of 4.5 MHz. The system is based on a silicon pixel sensor with a DEPFET as a central amplifier structure and has detection efficiency close to 100% for X-rays from 0.5 keV up to 10 keV. The sensor will have a size of approximately 210 × 210 mm composed of 1024 × 1024 pixels with hexagonal shape. Two hundred fifty six mixed signal readout ASICs are bump-bonded to the detector. They are designed in 130 nm CMOS technology and provide full parallel readout. The signals coming from the sensor are processed by an analog filter, immediately digitized by 8-bit ADCs and locally stored in an SRAM, which is able to record at least 640 frames. In order to fit the dynamic range of about 104 photons of 1 keV per pixel into a reasonable output signal range, achieving at the same time single 1 keV photon resolution, a non-linear characteristic is required. The proposed DEPFET provides the needed dynamic range compression at the sensor level. The most exciting and challenging property is that the single 1 keV photon resolution and the high dynamic range are accomplished within the 220 ns frame rate of the system. The key properties and the main design concepts of the different building blocks of the system are discussed. Measurements with the analog front-end of the readout ASIC and a standard DEPFET have already shown a very low noise which makes it possible to achieve the targeted single photon resolution for 1 keV photons at 4.5 MHz and also for 0.5 keV photons at half of the speed. In the paper the new experimental results obtained coupling a single pixel to an 8 × 8 ASIC prototype are shown. This 8 × 8 ASIC comprises the complete readout chain from the analog front-end to the ADC and the memory. The characterization of a newly fabricated non-linear DEPFET is presented for the first time.

Global alignment for high-dynamic range image generation

Abstract: Techniques and tools for high dynamic range (“HDR”) image generation and rendering are described herein. In several described embodiments, images having distinct exposure levels are aligned. In particular embodiments, the alignment of a reference image to a non-reference image is based at least in part on motion vectors that are determined using covariance computations. Furthermore, in certain embodiments, saturated areas, underexposed areas, and/or moving objects are ignored or substantially ignored during the image alignment process. Moreover, in certain embodiments, a hierarchical pyramid block-based scheme is used to perform local motion estimation between the reference image and the non-reference image.

Methods and apparatuses for image processing

Abstract: Methods and apparatuses for generating a low dynamic range image for a high dynamic range scene. In one aspect, a method to generate a low dynamic range image from a high dynamic range image, includes: determining one or more regions of the high dynamic range image containing pixels having values that are outside a first range and inside a second range; computing a weight distribution from the one or more regions; and generating the low dynamic range image from the high dynamic range image using the weight distribution. In another aspect, a method of image processing, includes: detecting one or more regions in a first image of a high dynamic range scene according to a threshold to generate a mask; and blending the first image and a second image of the scene to generate a third image using the mask.

State-of-the-Art and Future Directions of High-Performance All-Digital Frequency Synthesis in Nanometer CMOS

Abstract: The past several years have successfully brought all-digital techniques to the RF frequency synthesis, which could arguably be considered one of the last strong bastions of the traditionally-analog design approaches. With their high sensitivity and high dynamic range requirements, the RF circuits have long had a good excuse to avoid any possible source of digital switching activity. With the constant scaling of CMOS feature size and the merciless push for integration, the existence of almost free and powerful digital logic could not go unnoticed. Hence, the environment was ripe to transform the RF functions into digital realizations, as well as to apply digital assistance to help with the performance of RF circuits. This paper revisits the digitization journey of the traditional charge-pump PLL that has resulted in an all-digital frequency synthesizer with the best-in-class RF performance while occupying only a fraction of the silicon area and consuming a fraction of the power. The paper also offers a few novel techniques to further improve area, current consumption, testability, and reliability of frequency synthesizers.

Display assemblies and computer programs and methods for defect compensation

Abstract: The range of embodiments includes systems, methods, and apparatus for defect compensation that may be applied to displays having multiple imaging layers, such as high dynamic range displays, and/or to stereoscopic displays, such as autostereoscopic displays.

Display and detail enhancement for high-dynamic-range infrared images

Abstract: Dynamic range reduction and detail enhancement are two important issues for effectively displaying high-dynamic-range images acquired by thermal camera systems. They must be performed in such a way that the high dynamic range image signal output from sensors is compressed in a pleasing manner for display on lower dynamic range monitors without reducing the perceptibility of small details. In this paper, a new method of display and detail enhancement for high dynamic range infrared images is presented. This method effectively maps the raw acquired infrared image to 8-bit domain based on the same architecture of bilateral filter and dynamic range partitioning approach. It includes three main steps: First, a bilateral filter is applied to separate the input image into the base component and detail component. Second, refine the base and detail layer using an adaptive Gaussian filter to avoid unwanted artifacts. Then the base layer is projected to the display range and the detail layer is enhanced using an adaptive gain control approach. Finally, the two parts are recombined and quantized to 8-bit domain. The strength of the proposed method lies in its ability to avoid unwanted artifacts and adaptability in different scenarios. Its great performance is validated by the experimental results tested with two real infrared imagers.

High dynamic range electric field sensor for electromagnetic pulse detection.

Abstract: We design a high dynamic range electric field sensor based on domain inverted electro-optic (E-O) polymer Y-fed directional coupler for electromagnetic wave detection. This electrode-less, all optical, wideband electrical field sensor is fabricated using standard processing for E-O polymer photonic devices. Experimental results demonstrate effective detection of electric field from 16.7V/m to 750KV/m at a frequency of 1GHz, and spurious free measurement range of 70dB.

Pulse-Modulation Imaging—Review and Performance Analysis

Abstract: In time-domain or pulse-modulation (PM) imaging, the incident light intensity is not encoded in amounts of charge, voltage, or current as it is in conventional image sensors. Instead, the image data are represented by the timing of pulses or pulse edges. This method of visual information encoding optimizes the phototransduction individually for each pixel by abstaining from imposing a fixed integration time for the entire array. Exceptionally high dynamic range (DR) and improved signal-to-noise ratio (SNR) are immediate benefits of this approach. In particular, DR is no longer limited by the power-supply rails as in conventional complementary metal-oxide semiconductor (CMOS) complementary metal-oxide semiconductor active pixel sensors, thus providing relative immunity to the supply-voltage scaling of modern CMOS technologies. In addition, PM imaging naturally supports pixel-parallel analog-to-digital conversion, thereby enabling high temporal resolution/frame rates or an asynchronous event-based array readout. The applications of PM imaging in emerging areas, such as sensor network, wireless endoscopy, retinal prosthesis, polarization imaging, and energy harvesting are surveyed to demonstrate the effectiveness of PM imaging in low-power, high-performance machine vision, and biomedical applications of the future. The evolving design innovations made in PM imaging, such as high-speed arbitration circuits and ultra-compact processing elements, are expected to have even wider impacts in disciplines beyond CMOS image sensors. This paper thoroughly reviews and classifies all common PM image sensor architectures. Analytical models and a universal figure of merit - image quality and dynamic range to energy complexity factor are proposed to quantitatively assess different PM imagers across the entire spectrum of PM architectures.

White balance optimization with high dynamic range images

Abstract: Systems and methods to improve the white balance of a high dynamic range image are disclosed. In a particular embodiment, an imaging device includes a camera sensor and a processor, the processor configured to capture a lighter image and a darker image of a scene. The processor is then configured to white balance the lighter image based on the lighter regions of the image, and to white balance the darker image based on the darker regions of the image. The two images can then be combined to produce a final image.

Reconstruction of high contrast images for dynamic scenes

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 blind HDR problem for dynamic scenes. We develop a novel bottom-up segmentation algorithm through superpixel grouping which enables us to detect scene changes. We then employ a piecewise patch-based compositing methodology in the gradient domain to directly generate the ghost-free LDR image of the dynamic scene. Being a blind method, the primary advantage of our approach is that we do not assume any knowledge of camera response function and exposure settings while preserving the contrast even in the non-stationary regions of the scene. We compare the results of our approach for both static and dynamic scenes with that of the state-of-the-art techniques.

Improving the quality of high dynamic range images

Abstract: High dynamic range (HDR) photography is a useful luminance measurement tool but relies on the camera and lens used and photometric calibration for its accuracy, yet these aspects lack technical gui...

Perception-based high dynamic range video compression with optimal bit-depth transformation

Abstract: High Dynamic Range (HDR) technology is able to offer high levels of immersion with a dynamic range comparable to the Human Visual System (HVS). A primary drawback of HDR is that its memory and bandwidth requirements are significantly higher than for conventional video. The challenge is thus to develop means for efficiently compressing the video to a manageable bitrate without compromising perceptual quality. In this paper, we propose an HDR compression method based on an optimized bit-depth transformation, and HVS model based wavelet transform denoising. Experimental results indicate that the proposed method outperforms previous approaches and operates in accordance with characteristics of the HVS, tested objectively using a Visible Difference Predictor (VDP).

3D shape measurement of objects with high dynamic range of surface reflectivity.

Abstract: This paper presents a method that allows a conventional dual-camera structured light system to directly acquire the three-dimensional shape of the whole surface of an object with high dynamic range of surface reflectivity. To reduce the degradation in area-based correlation caused by specular highlights and diffused darkness, we first disregard these highly specular and dark pixels. Then, to solve this problem and further obtain unmatched area data, this binocular vision system was also used as two camera-projector monocular systems operated from different viewing angles at the same time to fill in missing data of the binocular reconstruction. This method involves producing measurable images by integrating such techniques as multiple exposures and high dynamic range imaging to ensure the capture of high-quality phase of each point. An image-segmentation technique was also introduced to distinguish which monocular system is suitable to reconstruct a certain lost point accurately. Our experiments demonstrate that these techniques extended the measurable areas on the high dynamic range of surface reflectivity such as specular objects or scenes with high contrast to the whole projector-illuminated field.

High Dynamic Range Image Watermarking Robust Against Tone-Mapping Operators

Abstract: High dynamic range (HDR) images represent the future format for digital images since they allow accurate rendering of a wider range of luminance values. However, today special types of preprocessing, collectively known as tone-mapping (TM) operators, are needed to adapt HDR images to currently existing displays. Tone-mapped images, although of reduced dynamic range, have nonetheless high quality and hence retain some commercial value. In this paper, we propose a solution to the problem of HDR image watermarking, e.g., for copyright embedding, that should survive TM. Therefore, the requirements imposed on the watermark encompass imperceptibility, a certain degree of security, and robustness to TM operators. The proposed watermarking system belongs to the blind, detectable category; it is based on the quantization index modulation (QIM) paradigm and employs higher order statistics as a feature. Experimental analysis shows positive results and demonstrates the system effectiveness with current state-of-art TM algorithms.

Operating a Device to Capture High Dynamic Range Images

Abstract: Some embodiments provide a method of operating a device to capture an image of a high dynamic range (HDR) scene. Upon the device entering an HDR mode, the method captures and stores multiple images at a first image exposure level. Upon receiving a command to capture the HDR scene, the method captures a first image at a second image exposure level. The method selects a second image from the captured plurality of images. The method composites the first and second images to produce a composite image that captures the HDR scene. In some embodiments, the method captures multiple images at multiple different exposure levels.

Generation of high dynamic range images from low dynamic range images in multi-view video coding

Abstract: Several approaches are disclosed for combining HDR and 3D image structure analysis and coding, in particular an encoding apparatus for encoding a first view high dynamic range image and a second view high dynamic range image comprising: first and second HDR image receivers(203, 1201) arranged to receive the first view high dynamic range image and a second view high dynamic range image; a predictor (209) arranged to predict the first view high dynamic range image from a low dynamic range representation of the first view high dynamic range image;and a view predictor (1203) to predict the second view high dynamic range image from at least one of the first view high dynamic range image, a low dynamic range representation of the second view high dynamic range image, or a low dynamic range representation of the first view high dynamic range image.

Predistortion Compensation of Nonlinearities in Channelized RF Photonic Links Using a Dual-Port Optical Modulator

Abstract: High dynamic range is a key requirement in analog applications. In multichannel optical signal processing applications, a wideband radio-frequency signal suffers from distortion from both in-channel and out-of-channel signals due to nonlinear modulator behavior. We demonstrate experimentally the compensation of nonlinearities occurring due to out-of-channel “cross-modulation” with a novel predistortion technique using a dual-port modulator. Predistortion compensation results in suppression of distortion by more than 25 dB.

High Dynamic Range Image Display With Halo and Clipping Prevention

Abstract: The dynamic range of an image is defined as the ratio between the highest and the lowest luminance level. In a high dynamic range (HDR) image, this value exceeds the capabilities of conventional display devices; as a consequence, dedicated visualization techniques are required. In particular, it is possible to process an HDR image in order to reduce its dynamic range without producing a significant change in the visual sensation experienced by the observer. In this paper, we propose a dynamic range reduction algorithm that produces high-quality results with a low computational cost and a limited number of parameters. The algorithm belongs to the category of methods based upon the Retinex theory of vision and was specifically designed in order to prevent the formation of common artifacts, such as halos around the sharp edges and clipping of the highlights, that often affect methods of this kind. After a detailed analysis of the state of the art, we shall describe the method and compare the results and performance with those of two techniques recently proposed in the literature and one commercial software.

Local tone mapping using the K-means algorithm and automatic gamma setting

Abstract: Tone mapping (TM) algorithms reproduce the high dynamic range (HDR) images on low dynamic range (LDR) display devices such as monitors or printers. In this paper, we propose a local TM algorithm, in which the HDR input is segmented using the K-means algorithm and a display gamma parameter is set automatically for each segmented region. The proposed TM algorithm computes the luminance of an input that is the radiance map generated from a set of LDR images acquired with varying exposure settings. Then, according to the bilateral filtered luminance, an image is divided into a number of regions using the K-means algorithm. The display gamma value is set automatically according to the mean value of each region. Then, the tone of HDR image is reproduced by a local TM method with adaptive gamma value. We generate the tone-mapped image using the proposed local TM. Computer simulation with real LDR images shows the effectiveness of the proposed local TM algorithm in terms of the visual quality as well as the local contrast. It can be used for contrast and color enhancement in various display and acquisition devices.

Content metadata enhancement of high dynamic range images

Abstract: Image data is encoded for distribution in a lower bit-depth format The image data has a range that is less than a maximum range and is mapped to the lower bit depth format using a mapping such that a ratio of a range of the lower bit depth representation to a maximum range of the lower bit depth representation is greater than a ratio of the range of the image data to a maximum range of the image data Metadata characterizing the mapping is associated with lower bit depth representation The metadata may be used downstream to reverse the mapping so that tonal detail is better reproduced