Multiple Exposure Technique Research Articles

Enhanced LDR Detail Rendering for HDR Fusion by TransU- Fusion Network

High Dynamic Range (HDR) images are widely used in automotive, aerospace, AI, and other fields but are limited by the maximum dynamic range of a single data acquisition using CMOS image sensors. High dynamic range images are usually synthesized through multiple exposure techniques and image processing techniques. One of the most challenging task in multiframe Low Dynamic Range (LDR) images fusion for HDR is to eliminate ghosting artifacts caused by motion.In traditional algorithms, optical flow is generally used to align dynamic scenes before image fusion, which can achieve good results in cases of small-scale motion scenes but causes obvious ghosting artifacts when motion magnitude is large. Recently, attention mechanisms have been introduced during the alignment stage to enhance the network’s ability to remove ghosts. However, significant ghosting artifacts still occur in some scenarios with large-scale motion or oversaturated areas. We proposea novel Distilled Feature TransformerBlock (DFTB) structure to distill and re-extract information from deep image features obtained after U-Net downsampling, achieving ghost removal at the semantic level for HDR fusion. We introduce a Feature Distillation Transformer Block (FDTB), based on the Swin-Transformer and RFDB structure. FDTB uses multiple distillation connections to learn more discriminative feature representations. For the multiexposure moving scene image fusion HDR ghost removal task, in the previous method, the use of deep learning to remove the ghost effect in the composite image has been perfect, and it is almost difficult to observe the ghost residue of moving objects in the composite HDR image. The method in this paper focuses more on how to save the details of LDR image more completely after removing the ghost to synthesize high-quality HDR image. After using the proposed FDTB, the edge texture details of the synthesized HDR image are saved more perfectly, which shows that FDTB has a better effect in saving the details of image fusion. Futhermore, we propose a new depth framework based on DFTB for fusing and removing ghosts from deep image features, called TransU-Fusion. First of all, we use the encoder in U-Net to extract image features of different exposures and map them to different dimensional feature spaces. By utilizing the symmetry of the U-Net structure, we can ultimately output these feature images as original size HDR images. Then, we further fuse high-dimensional space features using Dilated Residual Dense Block (DRDB) to expand the receptive field, which is beneficial for repairing over-saturated regions. We use the transformer in DFTB to perform low-pass filtering on low-dimensional space features and interact with global information to remove ghosts. Finally, the processed features are merged and output as an HDR image without ghosting artifacts through the decoder. After testing on datasets and comparing with benchmark and state-of-the-art models, the results demonstrate our model’s excellent information fusion ability and stronger ghost removal capability.

Injuries to the Chest Part 2 : Mediastinal Injuries

Blunt thoracic trauma comprises approximately 8% of all traumatic admissions in the United States. While chest wall injuries comprise much of this burden, mediastinal injuries, including cardiac and great vessel injuries, are being recognized more frequently given the diagnostic capabilities of modern CT imaging. In penetrating trauma, close proximity of structures in the mediastinal space, comes with a higher incidence of injury to multiple structures. Further, cardiac injury is estimated to comprise 10% of the mortality of gunshot wound victims, while more than 90% of great vessel injury is associated with penetrating injury, representing a significant burden of disease. Management and care of these injuries requires consideration of multiple details and exposure techniques. This article will address diagnosis, management and repair of esophageal, thoracic duct, cardiac, and great vessel injuries. This review contains 4 figures, 2 tables, and 49 references. Keywords: Mediastinal structures, esophageal injury, esophageal repair, thoracic duct injury, thoracic duct ligation, blunt cardiac injury, penetrating cardiac injury, blunt aortic injury, great vessel injury, endovascular stenting

Injuries to the Chest Part 2 : Mediastinal Injuries

Blunt thoracic trauma comprises approximately 8% of all traumatic admissions in the United States. While chest wall injuries comprise much of this burden, mediastinal injuries, including cardiac and great vessel injuries, are being recognized more frequently given the diagnostic capabilities of modern CT imaging. In penetrating trauma, close proximity of structures in the mediastinal space, comes with a higher incidence of injury to multiple structures. Further, cardiac injury is estimated to comprise 10% of the mortality of gunshot wound victims, while more than 90% of great vessel injury is associated with penetrating injury, representing a significant burden of disease. Management and care of these injuries requires consideration of multiple details and exposure techniques. This article will address diagnosis, management and repair of esophageal, thoracic duct, cardiac, and great vessel injuries. This review contains 4 figures, 2 tables, and 49 references. Keywords: Mediastinal structures, esophageal injury, esophageal repair, thoracic duct injury, thoracic duct ligation, blunt cardiac injury, penetrating cardiac injury, blunt aortic injury, great vessel injury, endovascular stenting

Diffracting-grain identification from electron backscatter diffraction maps during residual stress measurements: a comparison between the sin2ψ and cosα methods

X-ray diffraction (XRD) is a widely used technique to evaluate residual stresses in crystalline materials. Several XRD measurement methods are available. (i) The sin2ψ method, a multiple-exposure technique, uses linear detectors to capture intercepts of the Debye–Scherrer rings, losing the major portion of the diffracting signal. (ii) The cosα method, thanks to the development of compact 2D detectors allowing the entire Debye–Scherrer ring to be captured in a single exposure, is an alternative method for residual stress measurement. The present article compares the two calculation methods in a new manner, by looking at the possible measurement errors related to each method. To this end, sets of grains in diffraction condition were first identified from electron backscatter diffraction (EBSD) mapping of Inconel 718 samples for each XRD calculation method and its associated detector, as each method provides different sets owing to the detector geometry or to the method specificities (such as tilt-angle number or Debye–Scherrer ring division). The X-ray elastic constant (XEC) ½S 2, calculated from EBSD maps for the {311} lattice planes, was determined and compared for the different sets of diffracting grains. It was observed that the 2D detector captures 1.5 times more grains in a single exposure (one tilt angle) than the linear detectors for nine tilt angles. Different XEC mean values were found for the sets of grains from the two XRD techniques/detectors. Grain-size effects were simulated, as well as detector oscillations to overcome them. A bimodal grain-size distribution effect and `artificial' textures introduced by XRD measurement techniques are also discussed.

Over- and Under-Exposure Reconstruction of a Single Plenoptic Capture

Light field images, for example, taken with plenoptic cameras, offer interesting post-processing opportunities, including depth-of-field management, depth estimation, viewpoint selection, and 3D image synthesis. Like most capture devices, however, plenoptic cameras have a limited dynamic range, so that over- and under-exposed areas in plenoptic images are commonplace. We therefore present a straightforward and robust plenoptic reconstruction technique based on the observation that vignetting causes peripheral views to receive less light than central views. Thus, corresponding pixels in different views can be used to reconstruct illumination, especially in areas where information missing in one view is present in another. Our algorithm accurately reconstructs under- and over-exposed regions (known as declipping), additionally affording an increase in peak luminance by up to two f-stops, and a comparable lowering of the noise floor. The key advantages of this approach are that no hardware modifications are necessary to improve the dynamic range, that no multiple exposure techniques are required, and therefore that no ghosting or other artifacts are introduced.

Epoxy-based azo polymer for photofabricating surface-relief quasi-crystal structures

A new epoxy-based azo polymer (BP-AZ-CSMB), which contained chiral-substituted push-pull azo chromophores, was synthesized by the post-polymerization azo-coupling reaction. This newly synthesized polymer was characterized by 1H NMR, FTIR, GPC, UV-Vis, DSC and TGA. When exposed to interference patterns of laser beam (532 nm, 100 mW cm−2), BP-AZ-CSMB showed ability to quickly form surface-relief-gratings. Due to this property, quasi-crystal surface relief structures were feasibly fabricated on the BP-AZ-CSMB films by using the dual-beam multiple exposure technique. The quasi-crystal structures with 6-, 8-, 10-, 12-, 36-, and 72-fold rotation symmetry were successfully photofabricated.

Advanced plasma etch technologies for nanopatterning

Advances in patterning techniques have enabled the extension of immersion lithography from 65/45 nm through 14/10 nm device technologies. A key to this increase in patterning capability has been innovation in the subsequent dry plasma etch processing steps. Multiple exposure techniques, such as litho-etch-litho-etch, sidewall image transfer, line/cut mask, and self-aligned structures, have been implemented to solution required device scaling. Advances in dry plasma etch process control across wafer uniformity and etch selectivity to both masking materials have enabled adoption of vertical devices and thin film scaling for increased device performance at a given pitch. Plasma etch processes, such as trilayer etches, aggressive critical dimension shrink techniques, and the extension of resist trim processes, have increased the attainable device dimensions at a given imaging capability. Precise control of the plasma etch parameters affecting across-design variation, defectivity, profile stability within wafer, within lot, and across tools has been successfully implemented to provide manufacturable patterning technology solutions. IBM has addressed these patterning challenges through an integrated total patterning solutions team to provide seamless and synergistic patterning processes to device and integration internal customers. We will discuss these challenges and the innovative plasma etch solutions pioneered by IBM and our alliance partners.

2-DOF vibratory gyroscope fabricated by SU-8 based UV-LIGA process

This paper reports fabrication of 2-DOF vibratory gyroscope using SU-8 based UV-LIGA process. The device structure is designed to be symmetrical in order to match the resonance frequencies of drive and sense mode oscillators and also to minimize their relative temperature dependent drift. The overall arrangement is such that the two vibration modes do not affect each other and therefore, mechanical decoupling is achieved which helps in minimizing bias drift. The design is optimized to be compatible with the UV-LIGA process having 10 μm thick electroformed nickel as structural layer. Photolithography to create 11 μm thick SU-8 molds for electroforming sacrificial copper and structural nickel layer is optimized using multiple exposure technique that ensures near vertical side walls. Since the highly cross-linked SU-8 remaining after development is difficult to remove reliably from high aspect ratio structures without damage or alteration to the electroformed metals, a 2.45 GHz MW plasma etching process is developed with CF4/O2 mixes. The fabricated device is checked for off-plane misalignment between the stationary and movable comb fingers using white light interferometry and it is found to be almost negligible. Also, the prototype device is characterized for amplitude and phase spectral responses using Polytec MSA-500 Micro System Analyzer. The drive and sense mode resonance frequencies are observed at 7.3 and 7.1 kHz respectively against the mode matched designed frequency of 7.5 kHz.

An Enhanced Dynamic-Range CMOS Image Sensor Using a Digital Logarithmic Single-Slope ADC

Many kinds of wide-dynamic-range (DR) CMOS image sensors (CIS) have been developed, such as a multiple sampling, a multiple exposure technique, etc. However, those techniques have some drawbacks of noise increasing, large power consumption, and huge chip area. In this brief, a new digital logarithmic single-slope analog-to-digital converter (SS-ADC) with a digital counter is described. Since the proposed scheme is easily implemented with a simple algorithm, we can reduce power consumption and chip area drastically. Further, the logarithmic SS-ADC enhances the DR by 24 dB. The proposed ADC, which has been fabricated using a 0.13- μm CIS process, achieves a signal-to-noise-plus-distortion ratio of 57.6 dB at 50 kS/s.

A short history of superimposition: From spirit photography to early cinema

As several scholars have noted, the use of superimposition effects in cinema to conjure such apparitions as ghosts, fairies, devils, and other fantastic creatures finds a significant precedent in spirit photography, a spiritualist practice by which the image of one or more spirits was ‘magically’ captured on a photographic plate. However, arguing for a relationship of direct filiation between spirit photography and the tricks employed in film remains problematic, especially given that spirit pictures were entangled with matters of religious belief. This article calls for a more solid insertion of spiritualism’s visual culture into the pre-history of film practice, giving three main cases in support of the relationship between spirit photography and early cinema. Firstly, the commercial use of spirit photographs within the spiritualist movement suggests that the circulation of these images was not exclusively informed by matters of belief. Secondly, the popularization of exposures of spirit photography operated by numerous stage magicians in the late nineteenth century can contribute towards explaining the insertion of multiple-exposure techniques in the technical expertise of early filmmakers. Thirdly, a documented case in which spirit photographs were presented to a paying public in the vein of magic lantern entertainments demonstrates that the spiritualist visual culture intersected the nineteenth-century tradition of the projected image, too. Thus, by sketching a history of superimposition effects in photography, stage magic, magic lantern, and cinema, this article claims that visual representations of ghosts in the nineteenth century constantly wavered between religion and spectacle, fiction and realism, and still and moving pictures.

Experimental determination of self-similarity constant for converging cylindrical shocks

Guderley’s self-similarity solution r = r0(1 – t/t0)α for strong converging cylindrical shocks is investigated experimentally for three different gases with adiabatic exponents γ = 1.13; 1.40; and 1.66 and various values of the initial Mach number. Corresponding values of the similarity exponent α which determines the strength of shock convergence are obtained for each gas thus giving the variation of α with γ. Schlieren imaging with multiple exposure technique is used to track the propagation of a single shock front during convergence. The present experimental results are compared with previous experimental, numerical, and theoretical investigations.

Evaluation of EBT radiochromic film using a multiple exposure technique

Radiochromic film is a self developing two-dimensional dosimeter system that is widely used in radiotherapy. Since its development some 40 years ago many improvements have been made; however the sensitivity can vary across the film and a non-linear dose response remains. The former can be addressed using a double exposure technique; however this technique assumes that the response is linear so that the dose distribution is incorrectly measured. We are proposing the use of two homogenous exposures; one performed prior, the other after the irradiation to be measured. In this 'multiple exposure technique' (MET), the first homogenous exposure can be used to correct for variations in response in different parts of the film, while the second homogenous exposure allows correction for non-linearity of response with dose. The MET was tested with a 60° wedged field and an Intensity Modulated Radiation Therapy fluence map produced by a computerised treatment planning system. In the wedge field measurements, the MET profile showed agreement within 0.6 cGy for 80% of the field compared to ionisation chamber dose values. A comparison of a TPS generated fluence map dose distribution with one measured using conventionally calibrated EBT, and another measured with MET calibrated EBT, showed similar agreement. The MET would be particularly useful for the assessment of highly inhomogenous dose distributions with high maximum dose such as encountered in hypofractionated radiation therapy.

Automatic Level Control for Video Cameras towards HDR Techniques

We give a comprehensive overview of the complete exposure processing chain for video cameras. For each step of the automatic exposure algorithm we discuss some classical solutions and propose their improvements or give new alternatives. We start by explaining exposure metering methods, describing types of signals that are used as the scene content descriptors as well as means to utilize these descriptors. We also discuss different exposure control types used for the control of lens, integration time of the sensor, and gain control, such as a PID control, precalculated control based on the camera response function, and propose a new recursive control type that matches the underlying image formation model. Then, a description of commonly used serial control strategy for lens, sensor exposure time, and gain is presented, followed by a proposal of a new parallel control solution that integrates well with tone mapping and enhancement part of the image pipeline. Parallel control strategy enables faster and smoother control and facilitates optimally filling the dynamic range of the sensor to improve the SNR and an image contrast, while avoiding signal clipping. This is archived by the proposed special control modes used for better display and correct exposure of both low-dynamic range and high-dynamic range images. To overcome the inherited problems of limited dynamic range of capturing devices we discuss a paradigm of multiple exposure techniques. Using these techniques we can enable a correct rendering of difficult class of high-dynamic range input scenes. However, multiple exposure techniques bring several challenges, especially in the presence of motion and artificial light sources such as fluorescent lights. In particular, false colors and light-flickering problems are described. After briefly discussing some known possible solutions for the motion problem, we focus on solving the fluorescence-light problem. Thereby, we propose an algorithm for the detection of fluorescent lights from the image itself and define a set of remedial actions, to minimize false color and light-flickering problems.

A Dynamic Range Expansion Technique Using Dual Charge Storage in a CMOS APS and Multiple Exposures for Reduced Motion Blur

This paper presents a dynamic range expansion technique for CMOS image sensors using dual charge storage in a pixel and multiple exposures. Each pixel contains two photodiodes, PD1 and PD2 whose sensitivity can be set independently by the accumulation time. The difference of charge accumulation time in both photodiodes can be widely controlled to expand the dynamic range of the sensor. It allows flexible control of the dynamic range since the accumulation time in the PD2 signal is adjustable. The multiple exposure technique used in the sensor reduces the motion blur in the synthesized wide dynamic range image when capturing fast-moving objects. It also reduces the signal-to-noise ratio dip at the switching point of the PD1 signal to the PD2 signals in the synthesized wide dynamic range image. To reduce the read out time, a comparator-controlled selective readout of the PD1 and PD2 signals has been tested. The synthesis of the captured images to produce wide dynamic range image is also described. A wide dynamic range image sensor with 320x240 pixels has been implemented and tested. It is found that the use of 4 exposures in one frame for the short accumulation time signals is sufficient for the reduction of motion blur in the synthesized wide dynamic range image, and the signal-to-noise ratio dipping at the switching point of the PD1 to PD2 signals is reduced by 6 dB using 4 short-time exposures.

Tone-mapping functions and multiple-exposure techniques for high dynamic-range images

For real-time imaging with digital video cameras and high-quality with TV display systems, good tonal rendition of video is important to ensure high visual comfort for the user. Except local contrast improvements, High Dynamic Range (HDR) scenes require adaptive gradation correction (tone-mapping function), which should enable good visualization of details at lower brightness. We discuss how to construct and control improved tone-mapping functions that enhance visibility of image details in the dark regions while not excessively compressing the image in the bright image parts. The result of this method is a 21-dB expansion of the dynamic range thanks to improved SNR by using multiple- exposure techniques. This new algorithm was successfully evaluated in HW and outperforms the existing algorithms with 11 dB. The new scheme can be successfully applied to cameras and TV systems to improve their contrast.

Photofabrication of Two-Dimensional Quasi-Crystal Patterns on UV-Curable Molecular Azo Glass Films

In this work, two-dimensional surface quasi-crystal patterns were developed by using a novel azobenzene-containing amorphous material (IAC-4), which was newly synthesized for the application. IAC-4 contains a core of isosorbide moiety and two push-pull type azo chromophores as the inner part. The periphery of IAC-4 is functionalized with four cinnamate groups, which can undergo [2+2] photocycloaddition reaction upon UV light irradiation. The molecular design can allow IAC-4 to readily form surface relief structures upon Ar+ laser irradiation, and the formed structures can be further stabilized through a photo-cross-linking reaction induced by UV light irradiation. On the basis of the material, two-dimensional (2D) quasi-crystal structures with different rotation symmetries were successfully fabricated on the IAC-4 films by using the dual-beam multiple exposure technique. In contrast to the approach using photoresist, the quasi-crystal structures were fabricated through the photoinduced mass migration, and no subsequent wet-etch or dry-etch step was required in the process. The quasi-crystal structures with rotation symmetry as high as 60-fold could be feasibly fabricated through this approach. The surface patterns and fabrication method can be potentially applied in areas such as optics, communications, and security inspection.

A Dynamic Range Expansion Technique Using Dual Charge Storage in a CMOS APS and Multiple Exposures for Reduced Motion Blur

This paper presents a dynamic range expansion technique for CMOS image sensors using dual charge storage in a pixel and multiple exposures. Each pixel contains two photodiodes, PD1 and PD2 whose sensitivity can be set independently by the accumulation time. The difference of charge accumulation time in both photodiodes can be widely controlled to expand the dynamic range of the sensor. It allows flexible control of the dynamic range since the accumulation time in the PD2 signal is adjustable. The multiple exposure technique used in the sensor reduces the motion blur in the synthesized wide dynamic range image when capturing fast-moving objects. It also reduces the signal-to-noise ratio dip at the switching point of the PD1 signal to the PD2 signals in the synthesized wide dynamic range image. To reduce the read out time, a comparator-controlled selective readout of the PD1 and PD2 signals has been tested. The synthesis of the captured images to produce wide dynamic range image is also described. A wide dynamic range image sensor with 320x240 pixels has been implemented and tested. It is found that the use of 4 exposures in one frame for the short accumulation time signals is sufficient for the reduction of motion blur in the synthesized wide dynamic range image, and the signal-to-noise ratio dipping at the switching point of the PD1 to PD2 signals is reduced by 6 dB using 4 short-time exposures.

Novel Cell Stretching Micro Device for High Spatial and Temporal Resolution Observation

In this study, we have developed a novel cell stretching micro device to observe cellular response to mechanical stimuli with high spatial and temporal resolution. In conventional cell stretching device, rigid displacement of cell body during stretching operation is not negligible. And this rigid displacement makes it difficult to observe instant initial cellular response to stretching. The novel micro device is fabricated by applying MEMS technique, and consists of a transparent elastic micro chamber and a micro linkage mechanism. The micro chamber and linkage mechanism is fabricated by micro molding and multiple exposure technique of photoresist, respectively. We demonstrated availability of fabrication process, and evaluated performance of the micro device. When applying a stretch to chamber, rigid displacement was well suppressed. This result indicated a potential of this device to observe instant initial cellular response to stretching mechanical stimuli.

Holographic Fabrication of Periodic Microstructures in Dichromated Pullulan

One way to create photonic crystal structures is realized by holography [1–4]. In this study dual-beam multiple exposure technique is used to generate various lattice structures. In the dual-beam process, the photonic crystal structure is obtained by rotating the holographic recording material between exposures. A range of lattice structures can be obtained by varying the angle between two beams, and the rotation angle of holographic material. Previously, photonic structures have been recorded also in low-refractive index materials such as photoresists [4]. The holographic material used in this study is pullulan, doped with dichromate [5, 6]. Pullulan is a biopolymer with linear polysaccharide structure.

Fabrication of Compound Lattice by Holographic Lithography

Some compound lattices in photonic crystals with large completephotonic band gaps, such as the diamond structure and thetwo-dimensional hexagonal compound structure, is desired forfabrication. A novel method for fabrication of compound lattices byholographic lithography is reported. The key point is phase modulationby photoelectrical control and multiple-exposure techniques. Thistechnique introduces many advances: for instance, using the same coherentbeams and without changing the position of the sample duringmultiple-exposure.