Showing papers on "High dynamic range published in 2013"

Systems and methods for extending dynamic range of imager arrays by controlling pixel analog gain

Abstract: Array cameras and imager arrays configured to capture high dynamic range light field image data and methods of capturing high dynamic range light field image data in accordance with embodiments of the invention are disclosed. Imager arrays in accordance with many embodiments of the invention include multiple focal planes with associated read out and sampling circuitry. The sampling circuitry controls the conversion of the analog image information into digital image data. In certain embodiments, the sampling circuitry includes an Analog Front End (AFE) and an Analog to Digital Converter (ADC). In several embodiments, the AFE is used to apply different amplification gains to analog image information read out from pixels in a given focal plane to provide increased dynamic range to digital image data generated by digitizing the amplified analog image information. The different amplifications gains can be applied in a predetermined manner or on a pixel by pixel basis.

A reconfigurable camera add-on for high dynamic range, multispectral, polarization, and light-field imaging

Abstract: We propose a non-permanent add-on that enables plenoptic imaging with standard cameras. Our design is based on a physical copying mechanism that multiplies a sensor image into a number of identical copies that still carry the plenoptic information of interest. Via different optical filters, we can then recover the desired information. A minor modification of the design also allows for aperture sub-sampling and, hence, light-field imaging. As the filters in our design are exchangeable, a reconfiguration for different imaging purposes is possible. We show in a prototype setup that high dynamic range, multispectral, polarization, and light-field imaging can be achieved with our design.

High dynamic range and depth of field depth camera

Abstract: In order to maximize the dynamic range and depth of field for a depth camera used in a time of flight system, the light source is modulated at a plurality of different frequencies, a plurality of different peak optical powers, a plurality of integration subperiods, a plurality of lens foci, aperture and zoom settings during each camera frame time. The different sets of settings effectively create subrange volumes of interest within a larger aggregate volume of interest, each having their own frequency, peak optical power, lens aperture, lens zoom and lens focus products consistent with the distance, object reflectivity, object motion, field of view, etc. requirements of various ranging applications.

Automatic noise modeling for ghost-free HDR reconstruction

Abstract: High dynamic range reconstruction of dynamic scenes requires careful handling of dynamic objects to prevent ghosting. However, in a recent review, Srikantha et al. [2012] conclude that "there is no single best method and the selection of an approach depends on the user's goal". We attempt to solve this problem with a novel approach that models the noise distribution of color values. We estimate the likelihood that a pair of colors in different images are observations of the same irradiance, and we use a Markov random field prior to reconstruct irradiance from pixels that are likely to correspond to the same static scene object. Dynamic content is handled by selecting a single low dynamic range source image and hand-held capture is supported through homography-based image alignment. Our noise-based reconstruction method achieves better ghost detection and removal than state-of-the-art methods for cluttered scenes with large object displacements. As such, our method is broadly applicable and helps move the field towards a single method for dynamic scene HDR reconstruction.

3D High Dynamic Range dense visual SLAM and its application to real-time object re-lighting

Abstract: Acquiring High Dynamic Range (HDR) light-fields from several images with different exposures (sensor integration periods) has been widely considered for static camera positions. In this paper a new approach is proposed that enables 3D HDR environment maps to be acquired directly from a dynamic set of images in real-time. In particular a method will be proposed to use an RGB-D camera as a dynamic light-field sensor, based on a dense real-time 3D tracking and mapping approach, that avoids the need for a light-probe or the observation of reflective surfaces. The 6dof pose and dense scene structure will be estimated simultaneously with the observed dynamic range so as to compute the radiance map of the scene and fuse a stream of low dynamic range images (LDR) into an HDR image. This will then be used to create an arbitrary number of virtual omni-directional light-probes that will be placed at the positions where virtual augmented objects will be rendered. In addition, a solution is provided for the problem of automatic shutter variations in visual SLAM. Augmented reality results are provided which demonstrate real-time 3D HDR mapping, virtual light-probe synthesis and light source detection for rendering reflective objects with shadows seamlessly with the real video stream in real-time.

A 14b 2.5GS/s 8-way-interleaved pipelined ADC with background calibration and digital dynamic linearity correction

Abstract: Metastable events in ADC comparators cause large errors that cannot be tolerated in test and measurement applications that record data over extended time intervals. This work utilizes BiCMOS technology to provide high dynamic range analog-to-digital conversion at 2.5GS/s with a metastable error rate of less than one error per year and better than 78dB SFDR over a 1GHz BW.

High Dynamic Range Organic Temperature Sensor

Abstract: IC A IO N Due to the compatibility with large-area fabrication techniques and low fabrication costs involved, organic transistors have been actively researched and various kinds of chemical or physical sensors based on organics transistors have been developed. These sensors can be used for the detection of moisture, [ 1 ] glucose, [ 2 ] pressure, [ 3 , 4 ] light intensity, [ 5 ] and temperature. [ 3b ] For pressure-sensing applications, Bao et al. have demonstrated micro-structured polydimethylsiloxane (PDMS) pressure sensors with sensitivity down to 3 Pa. Someya et al. have also prepared pressure-sensor arrays with memory properties by using pressure-sensitive rubber alongside pentacene organic thin-fi lm transistor (OTFT) circuits. [ 3a ] In optical-sensor applications, Forrest et al. have shown an integrated OTFT-photodetector device with a sensitivity dynamic range of 12 bits for monochromatic light sensing at 580 nm. [ 5 ] Apart from pressure and light, heat is another important physical parameter that is often measured and thermal sensors have a lot of application potentials. High-sensitivity temperature sensors can be used for electronic skins, electronic health monitoring, and detecting patients’ body temperatures. However, unlike the pressure and optical sensors, OTFT-based temperature sensing devices with high sensitivity are yet to be demonstrated. As the glass transition temperatures of organic semiconductors are relatively low, the operating temperature of such organic temperature sensors is usually limited to around 100 ° C, making it extremely suitable for electronic skin or medical applications. Unfortunately the conductivity variation of the organic thin-fi lms in the resistor or diode structures between room temperature and 100 ° C is usually less than 10. [ 3b ] This results in limited sensitivity of the organic temperature sensors, especially in comparison with the silicon-based devices. [ 6 ]

Adaptive local tone mapping based on retinex for high dynamic range images

Abstract: In this paper, we present a new tone mapping technique for high dynamic range images based on the retinex theory. Our algorithm consists of two steps, global adaptation and local adaptation of the human visual system. In the local adaptation process, the Gaussian filter of the retinex algorithms is substituted with a guided filter to reduce halo artifacts. To guarantee good rendition and dynamic range compression, we propose a contrast enhancement factor based on the luminance values of the scene. In addition, an adaptive nonlinearity offset is introduced to deal with the strength of the logarithm function's nonlinearity. Experiments show that our algorithm provides satisfactory results while preserving details and reducing halo artifacts.

A Noise Adaptive Fuzzy Equalization Method for Processing Solar Extreme Ultraviolet Images

Abstract: A new image enhancement tool ideally suited for the visualization of fine structures in extreme ultraviolet images of the corona is presented in this paper. The Noise Adaptive Fuzzy Equalization method is particularly suited for the exceptionally high dynamic range images from the Atmospheric Imaging Assembly instrument on the Solar Dynamics Observatory. This method produces artifact-free images and gives significantly better results than methods based on convolution or Fourier transform which are often used for that purpose.

Two layer lossless coding of HDR images

Abstract: This report proposes a two layer lossless coding system for high dynamic range (HDR) images expressed in a floating point data format. Its encoder outputs compressed image data in two layers. From the base layer, a standard low dynamic range (LDR) image is decoded. Merging with the enhancement layer, the original HDR image is decoded without any loss. We introduce a reversible logarithmic mapping to reduce bit depth of pixel values. We also introduce bit plane classification to divide data into two layers. It was confirmed that our method has better coding performance than existing methods especially at high bit rate coding of LDR images.

41.1: Distinguished Paper: Viewer Preferences for Shadow, Diffuse, Specular, and Emissive Luminance Limits of High Dynamic Range Displays

Abstract: Once HDR displays were developed, a constant question persisted about how much dynamic range is needed for display. If one uses physical scene luminances or human visual system threshold detections to answer this question, the needed ranges are unachievable at exorbitant cost, and likely to remain so for decades. Therefore we designed studies to find the range that is preferred by human observers, and for suprathreshold appearances. Two studies address the diffuse reflective regions, and a third study tested preferences of highlight regions. Test images were specifically designed to test these limits without the perceptual conflicts that usually occur in these types of studies. For the diffuse range, we found displays capable of a dynamic range between 0.1 and 650 cd/m2 match the average preferences. However, to satisfy 90% of the population, a dynamic range from 0.005 to ∼3,000 cd/m2 is needed. Since a display should be able to produce values brighter than the diffuse white maximum, as in specular highlights and emissive sources, the highlight study concludes that the average preferred maximum luminance for highlight reproduction satisfying 50% of viewers is ∼2,500 cd/m2. This value increases to marginally over 20,000 cd/m2 when catering to 90%. Though there is some variability in preferred brightness between certain demographics, the call for a more capable display is still evident, as preferred luminances found in this study exceed even the best of consumer displays today.

High dynamic range photogrammetry for synchronous luminance and geometry measurement

Abstract: This study developed high dynamic range photogrammetry for synchronous acquisition of luminance of targets across a scene and their three dimensional coordinates XYZ in the field. The high dynamic ...

HDR image encoding and decoding methods and devices

Abstract: An image encoder includes an input for a high dynamic range input image (M_HDR); an image grading unit arranged to allow a human color grader to specify a color mapping from a representation (HDR_REP) of the high dynamic range input image defined according to a predefined accuracy, to a low dynamic range image (Im_LDR) by a human-determined color mapping algorithm. The image encoder is configured to output data specifying the color mapping (Fi(MP_DH)). Further, the image encoder includes an automatic grading unit configured to derive a second low dynamic range image (GT_IDR) by applying an automatic color mapping algorithm to one of the high dynamic range input image (M_HDR) and the low dynamic range image (Im_LDR).

Adaptive image synthesis for compressive displays

Abstract: Recent years have seen proposals for exciting new computational display technologies that are compressive in the sense that they generate high resolution images or light fields with relatively few display parameters. Image synthesis for these types of displays involves two major tasks: sampling and rendering high-dimensional target imagery, such as light fields or time-varying light fields, as well as optimizing the display parameters to provide a good approximation of the target content.In this paper, we introduce an adaptive optimization framework for compressive displays that generates high quality images and light fields using only a fraction of the total plenoptic samples. We demonstrate the framework for a large set of display technologies, including several types of auto-stereoscopic displays, high dynamic range displays, and high-resolution displays. We achieve significant performance gains, and in some cases are able to process data that would be infeasible with existing methods.

A real-time implementation of gradient domain high dynamic range compression using a local Poisson solver

Abstract: This paper presents a real-time hardware implementation of a gradient domain dynamic range compression algorithm for high dynamic range (HDR) images. This technique works by calculating the gradients of the HDR image, manipulating those gradients, and reconstructing an output low dynamic range image that corresponds to the manipulated gradients. Reconstruction involves solving the Poisson equation. We propose a Poisson solver that utilizes only local information around each pixel along with special boundary conditions, and requires a small and fixed amount of hardware for any image size, with no need to buffer the entire image. The hardware implementation is described in VHDL and synthesized for a field programmable gate array (FPGA) device. The maximum operating frequency achieved is fast enough to process high dynamic range videos with one megapixel per frame at a rate of about 100 frames per second. The hardware is tested on standard HDR images from the Debevec library. The output images produced have good visual quality.

Color Correction for Tone Reproduction

Abstract: High dynamic range images require tone reproduction to match the range of values to the capabilities of the display. For computational reasons as well as absence of fully calibrated imagery, rudimentary color reproduction is often added as a postprocessing step rather than integrated into the tone reproduction algorithm. However, in the general case this currently requires manual parameter tuning, although for some global tone reproduction operators, parameter settings can be inferred from the tone curve. We present a novel and fully automatic saturation correction technique, suitable for any tone reproduction operator, which exhibits better color reproduction than the state-ofthe-art and we validate its comparative effectiveness through psychophysical experimentation. Introduction Recent advances in both capture and display technologies allow images of a much wider dynamic range to be photographed, manipulated and displayed, better capturing the light of natural scenes and giving artists unparalleled freedom. Unlike prevalent consumer imaging pipelines though, no high dynamic range (HDR) standard has yet emerged defining the precise range, format or encoding to be used. As such, HDR data often needs to be compressed for display on most current displays, a process known as tonemapping [15, 2]. The aim of this paper is to preserve the appearance and information content of the image as much as possible while ensuring that it can be displayed on the chosen display device. To achieve that, tonemapping algorithms typically operate on the luminance of the image with little to no consideration for the color information present, leading to noticeable changes in the color appearance of the image, as shown in Figure 1. Commonly, tone compressed images acquire an over-saturated appearance when only the luminance channel is processed [12, 18]. Image appearance models, which can be seen as tone reproduction operators with integrated color appearance management [7, 9, 16], aim to reproduce color appearance, but they are designed with calibrated applications in mind and often come at the cost of higher computational complexity due to spatially varying processing. Despite their accuracy, these factors can limit their general applicability. Some solutions exist for correcting saturation mismatches after tone reproduction [12, 18]. This leads to computationally efficient correction, although we have observed that existing methods tend to create hue and luminance artefacts. Moreover, they require manual parameter selection which is strongly image and tone reproduction operator dependent. Recently, a psychophysical study was conducted for defining an automatic model to derive the parameters necessary for such corrections, but only allows parameters to be predicted when the tone compression or expansion function is global [12]. Instead, we propose a new approach for correcting saturation mismatches after dynamic range compression. We base our algorithm on insights from color science and on the observation that the amount of desaturation can be inferred from the non-linearity applied by the tone curve, irrespective of whether the tone reproduction operator was spatially varying or not. As such, our approach is parameter-free and agnostic to the operator used for mapping the dynamic range of the image or video. We find that our algorithm reproduces saturation significantly better than the current state-of-the-art. Related Work Differences in viewing conditions may result in significant mismatches in perceived color, which can be attributed to idiosyncrasies of the human visual system. To ensure that the appearance of a scene is correctly reproduced on a display, many issues will have to be taken into account, all broadly belonging to the field of color reproduction [8]. Image appearance models can be used to reproduce images as a human observer would see them under given viewing conditions [5, 16]. Such algorithms can be configured to yield calibrated color reproduction, and therefore do not require color post-processing. However, measurements of scene and display conditions are needed as inputs to image appearance models so that the human visual response can be accurately predicted. This requires specialist equipment such as photometers. These algorithms also tend to be computationally expensive, further limiting their use to offline processing. Dynamic range mismatches between scenes and display devices are therefore typically handled by tone reproduction operators. In essence, most of these algorithms focus on one dimension of the color gamut, namely compression along the luminance direction [15, 2]. Appearance effects are often ignored, leading to images which may appear too saturated. This problem can be mitigated by combining tone reproduction and color appearance algorithms [1]. However, this solution still requires calibrated data and measured viewing conditions to drive the color appearance component. A more common approach to saturation reproduction is to post-process the tone-mapped image, manually adjusting saturation to levels that appear plausible. Perhaps the most well-known technique for color correction involves the adjustment of color values by means of a power function, according to user parameter p ∈ [0,1] [18]. Given an original high dynamic range imTonemapped with Li et al. 2005 Corrected saturation reduced Corrected saturation enhanced Tonemapped with Reinhard et al. 2012 Figure 1. The same HDR image was tonemapped with different operators (left [10], right [16]). The left tonemapped image is overly saturated, while the tonemapping algorithm used on the right has reduced the saturation too far. With our method, both images are automatically corrected to have a very similar appearance by considering their relation with the original HDR image. (Source image from Mark Fairchild’s HDR Survey) age with input pixels Mo = (Ro,Go,Bo) specified in some linear RGB color space, and its associated per-pixel luminances Lo, it is first tonemapped with an operator f () that modifies the image’s luminances, Lt = f (Lo). The color-corrected image Mc is then produced with:

High Dynamic Range Imaging

Abstract: While real scenes produce a wide range of brightness variations, current cameras use low dynamic range image detector that typically provide 256 levels of brightness data at each pixel. We propose methods to create High Dynamic Range images, the method to enhance the dynamic range of is based on capturing multiple exposure photographs of the scene. Even if there are few methods available for creating HDR images, HDR display technologies still lag behind. We present a tone mapping algorithm to display HDR images on Low Dynamic Range display devices. We also deal with histogram manipulation for painterly effect on output. Applications of HDR images are discussed in brief. An algorithm to create HDR images for still scenes in Color Filter Array (CFA) domain is proposed and successfully implemented.

Fast tone mapping for high dynamic range images

Abstract: We present a fast, effective and flexible tone reproduction method that preserves visibility and contrast impression of high dynamic range scenes in low dynamic range reproduction devices. A single parameter controls the visibility and contrast in a simple and elegant manner and at interactive speed. The new method is simple to use and is computationally highly efficient. Experiments show that the technique produces good results on a variety of high dynamic range images. The method can also be used to enhance ordinary low dynamic range digital images.

Expert system for prediction of changes to local environment

Abstract: Disclosed is a photometer that employs high dynamic range (HDR) image processing and manipulation algorithms for capturing and measuring real-time sky conditions for processing into control input signals to a building's automated fenestration (AF) system, daylight harvesting (DH) system and HVAC system. The photometer comprises a color camera and a fitted fish-eye lens to capture 360-degree, hemispherical, low dynamic range (LDR) color images of the sky. Both camera and lens are housed in a sealed enclosure protecting them from environmental elements and conditions. In some embodiments the camera and processes are controlled and implemented by a back-end computer.

High quality factor l-band active inductor-based band-pass filters

Abstract: In this letter, a tunable high-Q active inductor with high dynamic range is presented. The equivalent inductance and resistance values can be tunable in a wide frequency range by changing the compe...

High Dynamic Range Imaging: Sensors and Architectures

Abstract: Illumination is a crucial element in many applications, matching the luminance of the scene with the operational range of a camera. When luminance cannot be adequately controlled, a high dynamic range (HDR) imaging system may be necessary. These systems are being increasingly used in automotive on-board systems, road traffic monitoring, and other industrial, security, and military applications. This book provides readers with an intermediate discussion of HDR image sensors and techniques for industrial and non-industrial applications. It describes various sensor and pixel architectures capable of achieving HDR imaging, as well as software approaches to make high dynamic range images out of lower dynamic range sensors or image sets. Some methods for automatic control of exposure and dynamic range of image sensors are also introduced.

Continuous-Wave THz Homodyne Spectroscopy and Imaging System With Electro-Optical Phase Modulation for High Dynamic Range

Abstract: We present a terahertz (THz) continuous-wave coherent homodyne spectroscopy and imaging system based on THz phase control using electrooptic (EO) phase modulation for fast measurement without mechanical delay movement. After describing the degradation effects of detection signal by the optical laser noise and parasitic amplitude modulation, we propose the push-pull EO phase modulation with optical delay control for dynamic range enhancement. Using wideband unitraveling-carrier photodiode and InGaAs photoconductive antenna, spectroscopy up to a 1.5-THz frequency range and imaging are demonstrated.

Device and method for high dynamic range image display

Abstract: The invention is applicable to the technical field of image processing and provides a device and a method for high dynamic range image display. The method includes: segmenting a high dynamic range image according to preset image segmentation algorithm to acquire a plurality of image subblocks; adjusting the brightness value of any pixel point in each image subblock according to attribute information of each image subblock, the brightness value of the pixel point at the corresponding position of each image subblock and the preset image linear mapping relation; and generating and displaying a low dynamic range image according to the adjusted brightness value of each pixel point in each image subblock. Displaying effects of the generated low dynamic range image are greatly improved by adjusting the brightness value of any pixel point in each image subblock according to attribute information of each image subblock, the brightness value of the pixel point at the corresponding position of the high dynamic range image and the preset image linear mapping relation.

Image capture apparatus, method of controlling image capture apparatus, and electronic device

Abstract: An image capture apparatus is provided that is capable of accurately determining exposure conditions of multiple images to be used in high dynamic range compositing in a short duration, based on a captured image. A scene dynamic range is computed based on luminance information obtained from an image captured with a standard exposure according to a luminance zone to be prioritized in high dynamic range shooting and luminance information obtained from an image captured with an over-exposure or an under-exposure relative to the standard exposure. An exposure range of multiple images for creating a high dynamic range image is determined according to the computed dynamic range.

Fast, Broadband, and High-Dynamic Range 3-D Field Strength Probe

Abstract: Electromagnetic fields are conventionally measured using diode detectors or thermocouple detectors. The diode is limited in dynamic range. The dynamic range is important when considering modern pulsed wireless systems with a high peak-average ratio or crest factor. The thermocouple is too slow to measure fast changing fields, such as the ones created by the pulse-modulated wireless system, and in reverberation chambers. In modern mobile phones, a radio signal strength indicator circuit, with a logarithmic amplifier, is used to measure, and via a feedback circuit, control the output power. Devices with a frequency range up to 10 GHz, a dynamic range of more than 80 dB and response time less than 50 ns are available. Three orthogonal monopole antennas connected to three logarithmic amplifiers result in a fast, broadband, and high-dynamic range field strength probe. The concept is described and simulation results are shown. Prototype probes have been built, and the design data and results of experiments are given. Possible applications and additional features of the probes are described.

Low Noise High Efficiency 3.75 µm and 2.8 µm Global Shutter CMOS Pixel Arrays

Abstract: Our history of GS pixel development started at Photobit Corporation in the late 90s by creating the 1 generation of GS sensors for machine vision applications with pixel size in the range of 12μm to 16μm, sensor format up to 512x512 pixels, and frame rate up to 5000FPS. Sensors achieved quantum efficiency (QE) of 40% and noise floor of 70e [1]. A 2 generation of Global shutter devices was developed in 2005 by the Micron Imaging group [2]. Pixel size was reduced to 6.0μm, QE was increased to 50%, and noise floor was reduced to ~25e by using soft reset of the floating diffusion. High dynamic range feature was also added to design of the sensor. The range of applications was significantly extended as these devices are successfully utilized now in automotive, surveillance, and gaming applications. True correlated double sampling (CDS) technique was introduced in the 3 generation of Aptina GS pixels to significantly reduce the sensor noise floor. Additionally, the pixel shared architectures allowed further shrinking of the pixel size. QE was increased to 70%. Progressing from a floating diffusion (FD) as a pixel memory to a dedicated in-pixel pinned diode charge storage allowed significant reduction of the readout noise (up to 2.4e) and total noise floor (8e). The 3 generation pixel and sensors were first presented in 2011 [3]. In this paper we present the progress in pixel performance improvement that was made since then and also present development of next generation of GS pixel design allowing for the further pixel shrink and performance improvement.

High Dynamic Range image & video compression a review

Abstract: High Dynamic Range (HDR) imaging technologies can provide high levels of immersion through a dynamic range that meets and even exceeds the instantaneous range of the Human Visual System (HVS). This increase in the level of immersion comes at the cost of significantly higher bit-rate requirements compared to those associated with conventional imaging technologies. As a result, efficient HDR-relevant coding solutions have to be developed. In this paper, we present a review of existing HDR image and video coding methods, thus establishing the current state of the art. We additionally present some of our own recent results in this area.

Apparatus and method for generating high dynamic range image from which ghost blur is removed

Abstract: Disclosed are an apparatus and a method for generating a high dynamic range (HDR) image from which a ghost blur is removed. The apparatus may include an HDR weight map calculation unit to calculate an HDR weight map for multiple exposure frames that are received, a ghost probability calculation unit to calculate a ghost probability for each image by verifying a ghost blur for the multiple exposure frames, an HDR weight map updating unit to update the calculated HDR weight map based on the calculated ghost probability, and a multi-scale blending unit to generate an HDR image by reflecting the updated HDR weight map to the multiple exposure frames.