High Dynamic Range Imaging System Research Articles

Hybrid High Dynamic Range Imaging fusing Neuromorphic and Conventional Images.

Reconstruction of high dynamic range image from a single low dynamic range image captured by a conventional RGB camera, which suffers from over- or under-exposure, is an ill-posed problem. In contrast, recent neuromorphic cameras like event camera and spike camera can record high dynamic range scenes in the form of intensity maps, but with much lower spatial resolution and no color information. In this paper, we propose a hybrid imaging system (denoted as NeurImg) that captures and fuses the visual information from a neuromorphic camera and ordinary images from an RGB camera to reconstruct high-quality high dynamic range images and videos. The proposed NeurImg-HDR+ network consists of specially designed modules, which bridges the domain gaps on resolution, dynamic range, and color representation between two types of sensors and images to reconstruct high-resolution, high dynamic range images and videos. We capture a test dataset of hybrid signals on various HDR scenes using the hybrid camera, and analyze the advantages of the proposed fusing strategy by comparing it to state-of-the-art inverse tone mapping methods and merging two low dynamic range images approaches. Quantitative and qualitative experiments on both synthetic data and real-world scenarios demonstrate the effectiveness of the proposed hybrid high dynamic range imaging system. Code and dataset can be found at: https://github.com/hjynwa/NeurImg-HDR.

Luminance calibration of a full sky HDR imaging system using sky scanner measurements

A full sky High Dynamic Range imaging system, based on a Single-Lens Reflex camera with a fisheye lens, has been constructed and calibrated with a sky scanner luminance meter. The method considers the geometrical, spectral, timing and orientation issues between instruments. The calibration data sets, having nearly simultaneous measurements under stable sky conditions, were obtained from approximately one month of data using selection variables based in the experimental design. For luminance estimation we use the standard CIEY RGB combination and a Spectrally Matched Luminance (SML) predictor, matching the spectral response of the instruments. With 738 calibration points having luminances up to 23.6kcd/m2, covering 98.5% of the sky luminance range, CIEY is linearly correlated with sky scanner measurements with a coefficient of determination R2=0.9927 and a Root Mean Squared Error (RMSE) of 7.7%. SML gives better results, with R2=0.9973 and RMSE=5.3%. With 253 calibration points with luminances up to 12.9kcd/m2, comprising 94.1% of the sky luminance range, both predictors clearly improve, with R2=0.9964 and RMSE=4.1% in case of CIEY and R2=0.9982 and RMSE=2.9% in case of SML.

Pixel-level mapping method in high dynamic range imaging system based on DMD modulation

In order to build pixel-to-pixel correspondence between the CCD camera and digital micromirror device (DMD) in high dynamic range (HDR) imaging system, we proposed an absolute phase mapping method based on the first partial derivatives of phase-shifted composite fringes in this paper. Compared with the conventional phase mapping method, the needed fringe patterns of our method are reduced by one time, which improves the mapping efficiency. Meanwhile, experimental results show the proposed method has an accuracy improvement over the existing methods. The root mean square error is within 0.11 pixels in both the horizontal and vertical directions, reaching the sub-pixel mapping accuracy and indicating the superiority of our method. Finally, we combined the proposed mapping method with the imaging system and achieved high dynamic range imaging by photographing the surface of highlighted object, which verified the validity and practicability of our method.

Model for High Dynamic Range Imaging System Using Hybrid Feature Based Exposure Fusion

Abstract The luminous value is high for many natural scenes, which causes loss of information and occurs in dark images. The High Dynamic Range (HDR) technique captures the same objects or scene for multiple times in different exposure and produces the images with proper illumination. This technique is used in the various applications such as medical imaging and observing the skylight, etc. HDR imaging techniques usually have the issue of lower efficiency due to capturing of multiple photos. In this paper, an efficient method is proposed for HDR imaging technique to achieve better performance and lower noise. The Luminance-Chrominance-Gradient High Dynamic Range (LCGHDR) method is proposed to obtain the proper luminous value of images. The same scenario is captured at different exposure are processed by the proposed method. Based on these feature values extracted from the different images and exposure fusion technique was developed that helps for the proper imaging. This experiment was evaluated and analyzed by comparing with the other methods, which showed the efficiency of the proposed method. This method needs only 124.594 seconds for the computation, while existing method need 139.869 seconds for the same number of images.

Binocular high dynamic range imaging system based on digital micromirror device

In the applications of scientific imaging and space exploration, the dynamic range of imaging systems is usually required to reach more than 120 dB. In order to observe a highly dynamic scene in real time, we designed an imaging system based on a digital micromirror device (DMD) that is used as a spatial light modulator. First, we designed a binocular highly dynamic light-adjusting system based on a DMD according to the DMD’s optical structure. Second, in order to realize the registration between the micromirrors of a DMD and pixels of the two cameras, a pixel-matching algorithm was developed. Finally, we introduce a novel light-adjusting algorithm that can recover the highly dynamic data of the dynamic scene. Experiments showed that the deviation between the DMD and the two cameras is reduced to 0.48 pixels after correction, and that bright and dark targets in a high-dynamic-range scene can both be displayed simultaneously in one image with high quality after light adjustment. The dynamic range of the system is theoretically 209 dB, which meets the requirements of high-dynamic-range observation.

No-reference quality metric for high dynamic range imaging system based on curvature analysis in tensor domain

No-reference quality metric for high dynamic range imaging system based on curvature analysis in tensor domain

Visual glare limits of HDR displays in medical imaging

Emerging display technologies are proposing monitors for medical imaging with an extended dynamic range of luminance. Those devices offer the opportunity to extend the range of visual information displayed, but the limits of the human visual system (HVS) in perceiving such information can cancel the advantages. To investigate this problem, we present a set of experiments, to assess the visual response of the HVS to controlled high dynamic range (HDR) content. They analyse the effects of glare. Using a typical HDR display, tailored for medical imaging applications, they first study the dependence of the visible dynamic range from the inter‐ocular glare, induced by different backgrounds, then the effect of glare on the detection of test elements on medical radiographic images. Finally, they assess the influence of luminance‐equivalent backgrounds with different structure in the detection of test patches. The results of the experiments confirm the glare as a major player in influencing visual information detection. Glare has a significant impact in limiting the amount of visual information actually perceived, consequently limiting analysis capabilities of such images. This confirms the importance of investigating and considering the characteristics of human vision in the design and test of HDR imaging systems.

High Dynamic Range Imaging system for Energy Optimization in Daylight - Artificial Light Integrated Scheme

This paper explains High Dynamic Range Imaging (HDRI) technology for the control and optimization of visual comfort, thermal comfort and energy consumption in daylight-artificial light integrated scheme. The objective of this work is to incorporate image sensors, Wi-Fi and ZigBee to make an economical solution for reducing energy consumption while improving visual comfort levels. The camera based fuzzy model presented determines the position of blinds ensuring visual and thermal comfort by reducing glare and maintaining uniformity. MATLAB – SIMULINK technical computing and visualizing environment is used to obtain the complete system including making HDR images, calibration of camera, formulation of control algorithm for artificial light and window blind control as well as to analyse the quality aspects of daylight-artificial light integrated scheme.

High Dynamic Range Imaging System for Energy Optimization in Daylight – Artificial Light Integrated Scheme

High Dynamic Range Imaging System for Energy Optimization in Daylight – Artificial Light Integrated Scheme

利用DMD获取高动态范围图像技术

In some scenarios,very bright objectives and very dark objectives exist at the same time. The traditional imaging device can not detect these objectives,and then high dynamic range image acquiring system is needed to detect them. Digital Micro-mirror Devices( DMD) is used to get high dynamic range image,which is the most advanced technology at present. In this paper,a pixel level high dynamic range imaging system is designed based on DMD. The system is composed of optical system,mechanical system,DMD pixel level dimming algorithm and imaging unit. The secondary imaging system is used in the optical system. The first imaging optical structure is image space telecentric system,and the second imaging optical structure is magnification 1: 1 quasi-symmetric system. Wrapping technology of optical elements and centering machining process are used in mechanical system,and the optical assembly precision reaches second level. The method searching for single DMD pixel's controlling weight is used in dimming algorithm. The science class 12 bit s CMOS and 8bit CCD can be used simultaneously in imaging unit. The correctness of the system is proved by the prototype.The image dynamic range can reach 140 d B,much higher than 78 d B dynamic range of traditional cameras.

JUNGFRAU 0.2: prototype characterization of a gain-switching, high dynamic range imaging system for photon science at SwissFEL and synchrotrons

JUNGFRAU (adJUstiNg Gain detector FoR the Aramis User station) is a two-dimensional pixel detector for photon science applications at free electron lasers and synchrotron light sources. It is developed for the SwissFEL currently under construction at the Paul Scherrer Institute, Switzerland. Characteristics of this application-specific integrating circuit readout chip include single photon sensitivity and low noise over a dynamic range of over four orders of magnitude of photon input signal. These characteristics are achieved by a three-fold gain-switching preamplifier in each pixel, which automatically adjusts its gain to the amount of charge deposited on the pixel. The final JUNGFRAU chip comprises 256 × 256 pixels of 75 × 75 μm2 each. Arrays of 2 × 4 chips are bump-bonded to monolithic detector modules of about 4 × 8 cm2. Multi-module systems up to 16 Mpixels are planned for the end stations at SwissFEL. A readout rate in excess of 2 kHz is anticipated, which serves the readout requirements of SwissFEL and enables high count rate synchrotron experiments with a linear count rate capability of > 20 MHz/pixel. Promising characterization results from a 3.6 × 3.6 mm2 prototype (JUNGFRAU 0.2) with fluorescence X-ray, infrared laser and synchrotron irradiation are shown. The results include an electronic noise as low as 100 electrons root-mean-square, which enables single photon detection down to X-ray energies of about 2 keV. Noise below the Poisson fluctuation of the photon number and a linearity error of the pixel response of about 1% are demonstrated. First imaging experiments successfully show automatic gain switching. The edge spread function of the imaging system proves to be comparable in quality to single photon counting hybrid pixel detectors.

Characterization method for a multispectral high-dynamic-range imaging system

An accurate characterization method for a multispectral high-dynamic-range (HDR) imaging system is proposed by combining multispectral and HDR imaging technologies. The multispectral HDR imaging system, which can acquire the visible spectrum at many wavelength bands, can provide an accurate color reproduction and physical radiance information of real objects. An HDR camera is used to capture an HDR image without multiple exposures and a liquid crystal tunable filter (LCTF) is used to generate multispectral images. Due to its several limitations in the multispectral HDR imaging system, a carefully designed and an innovative characterization algorithm is presented by considering a logarithmic camera response of the HDR camera and different spectral transmittance of the LCTF. The proposed method efficiently and accurately recovers the full spectrum from the multispectral HDR images using a transformation matrix and provides device-independent color information (e.g., CIEXYZ and CIELAB). The transformation matrix is estimated by training the estimated sensor responses from a multispectral HDR imaging system and the reflectance measurements from a spectroradiometer using Moore–Penrose pseudoinverse matrix.

3D laser scanner system using high dynamic range imaging

Because of its high measuring speed, moderate accuracy, low cost and robustness in the industrial field, 3D laser scanning has been widely used in a variety of applications. However, the measurement of a 3D profile of a high dynamic range (HDR) brightness surface such as a partially highlighted object or a partial specular reflection remains one of the most challenging problems. This difficulty has limited the adoption of such scanner systems. In this paper, an optical imaging system based on a high-resolution liquid crystal on silicon (LCoS) device and an image sensor (CCD or CMOS) was built to adjust the image's brightness pixel by pixel as required. The radiance value of the image captured by the image sensor is constrained to lie within the dynamic range of the sensor after an adaptive algorithm of pixel mapping between the LCoS mask plane and image plane through the HDR imaging system is added. Thus, an HDR image was reconstructed by the LCoS mask and the CCD image on this system. The significant difference between the proposed system and a traditional 3D laser scanner system is that the HDR image was used to calibrate and calculate the 3D profile coordinate. Experimental results show that HDR imaging can enhance 3D laser scanner system environmental adaptability and improve the accuracy of 3D profile measurement.

基于互信息的高动态范围成像系统成像质量分析

For optimizing design of the High Dynamic Range Imaging system and evaluating its performance perfectly,the information theory is applied to the High Dynamic Range Imaging system,the High Dynamic Range Imaging system is considered as a communication system,and the image quality of High Dynamic Range Imaging system is evaluated according to the end-to-end mutual information.Introducing the influence of LCoS as a spatial light modulator to CMOS sampling imaging model,mathematical model of the High Dynamic Range Imaging system based on mutual information is established.According to the model,the factors,such as the ratio of LCoS pixel number to CMOS pixel number,aperture ratio of LCoS and CMOS pixel,relative displacement and relative rotation angle,which affect the mutual information,and the reasons why the system image quality decline are analyzed.According to computer simulation,the relationships between the ratio of LCoS pixel number to CMOS pixel number and the mutual information,aperture ratio of LCoS and CMOS pixel and the mutual information,relative displacement and the mutual information,relative rotation angle and the mutual information are demonstrated,and the influence of these factors on the mutual information is analyzed.The simulation results show that the best matching condition between LCoS array and CMOS array is that one LCoS pixel corresponds to one CMOS pixel with smaller CMOS pixel,higher aperture of LCoS and CMOS pixel,no relative displacement and no relative rotation.

Stability research of one kind of high dynamic range imaging system

High dynamic range imaging (HDRI) has become a topic of intense research interest in many fields. One kind of HDRI system based on the spatial light modulator (SLM) has a problem with output image instability because of feedback modulation. The HDRI system is introduced, and then a feedback modulation model for the HDRI system is established to discuss the oscillation reason for the output images. The relationship between the input light intensity and the feedback progress is analyzed. A method that adjusts the modulate index of the SLM is proposed to solve the instability problem, and the stability conditions are given to obtain stable images. Lastly, experimental images prove that the feedback model is correct and the output image with high dynamic range is stable.

High Dynamic Range Imaging by Fusing Multiple Raw Images and Tone Reproduction

This paper presents an integrated color imaging system for taking images in extremely high dynamic range scenes. The system first fuses several differently exposed raw images to acquire more intensity information. The effective dynamic range of the image raw data can be extended to 256 times if five differently exposed images are fused. Then it runs edge detection iterations to extract the image details in different luminance levels. The proposed tone reproduction algorithm equalizes the histogram of the extracted fine edges which tends to assign larger dynamic range for highly populated regions. Finally, the local contrast enhancement is performed to further refine the image details. The experimental results show that the proposed high dynamic range imaging system has good performance on both tone and color reproduction.

High dynamic range quantitative image depth profiling of boron in patterned silicon dioxide on silicon

A high sensitivity, high dynamic range imaging system has been developed for secondary ion mass spectrometry (SIMS). The combination of stigmatic imaging and dynamic primary ion beam sputtering provided by the ion microscope (Cameca IMS‐3f) permits acquisition of SIMS image depth profiles, i.e., three‐dimensional maps of elemental composition. In this study a methodology was developed which allows transformation of raw image ion intensities to elemental concentration. First, the response of the dual microchannel plate/phosphor screen charge coupled device detector was determined and correction procedures developed from this information were applied to an SiO2 on Si sample. Sensitivity factors were then generated for an impurity, boron, in the SiO2 and Si, respectively. The detector correction and elemental sensitivity factors were applied to the entire image depth profile set in an effort to produce a quantitative image depth profile. Local area depth profile of selected areas of the sample were then generated and compared to depth profiles produced using the standard SIMS detector, the electron multiplier.