Digital Camera System Research Articles

Digital Photography Using a High-Transmittance Electro-Optical Iris

In this paper, a tunable electro-optical iris with high transmittance, based on polymer dispersed liquid crystal (PDLC) material, and a relevant image enhancement method are combined for digital photography. Our device is controllable by adjusting the voltage and no mechanical and moving components are required so as to improve the stability. The experiments show that transmittance of light throughput is tunable from nearly 0% to 77% by gradually increasing driving voltage. The digital camera system using our PDLC iris can capture the high-contrast image in real-scene photography. To further improve the image quality, we develop an iterative image enhancement method that is able to improve the signal-to-noise ratio by ~10 times and increase the image brightness simultaneously. The combination of the PDLC electro-optical device and a variant of the enhancement algorithm can also have the potential to be applied in optical imaging and sensing.

An experimental study of the mechanical and fracturing behavior in PMMA specimen containing multiple 3D embedded flaws under uniaxial compression

This paper studies the mechanical and fracture behavior of poly methyl methacrylate (PMMA) specimens containing multiple embedded flaws, under uniaxial compression. The initiation, propagation, coalescence of cracks, and failure of specimens are captured by a high-speed digital video camera system. Six types of cracks and three modes of crack coalescence are captured in the PMMA specimens. The experimental observations show that the effects of the flaw angle on crack propagation and coalescence are stronger than the non-overlapping length. Furthermore, the peak strength and crack initiation stress show regular change with increasing in the flaw angle and the non-overlapping length.

Compact self-interference incoherent digital holographic camera system with real-time operation.

The video recording-capable compact incoherent digital holographic camera system is proposed. The system consists of the linear polarizer, convex lens, geometric phase lens, and the polarized image sensor. The Fresnel hologram is recorded by this simple configuration in real time. The system parameters are analyzed and evaluated to record a better-quality hologram in a compact form-factor. The real-time holographic recording and its digitally reconstructed video playback are demonstrated with the proposed system.

Experimental study on effects of freeze‐thaw fatigue damage on the cracking behaviors of sandstone containing two unparallel fissures

AbstractThis paper investigates the effects of freeze‐thaw (FT) fatigue damage on the cracking behaviors of sandstone specimens containing two unparallel fissures under uniaxial compression. First, the effects of FT fatigue damage and fissure angle on the mechanical properties of sandstone specimens are analyzed. Second, the real‐time cracking process of sandstone specimens is captured by a high‐speed digital video camera system. Seven crack coalescence patterns are observed in this experiment. Local strong fatigue‐damaged zones, which are visualized as white zones, are observed in the specimens subjected to FT cycles during loading. Finally, scanning electron microscopy (SEM) observations show that the local strong fatigue‐damaged zones mainly consisted of microcracks and micropores induced by the FT fatigue damage. These experimental results are helpful for improving the understanding of the cracking process in cold‐region engineering.

Face skin tone adaptive automatic exposure control

In face-priority automatic exposure control in digital camera systems, exposure adjustment is typically made irrespective of the face skin tone, i.e. how dark or bright the face is. As a result, a face can become over exposed when it is present against a very dark background, or become under exposed when it is present against a very bright background, depending on the face skin tone and scene content. Adapting the exposure control to the face skin tone will result in well-exposed faces in various capture scenarios, and hence better image quality.This paper presents a novel face skin tone adaptive automatic exposure control solution. Using a well-trained neural network based face skin tone predictor, the likelihoods of dark and bright face skin tones are calculated. An algorithm adjusts the bounds of the target brightness of the exposure control based on the face skin tone likelihoods and a set of configuration parameters. The face skin tone adaptive brightness bounds then guide the frame exposure adjustment. Experimental results demonstrate the outperformance of the proposed solution over conventional exposure control that does not take into account the face skin tone information.

Experimental study on crack coalescence behavior of double unparallel fissure-contained sandstone specimens subjected to freeze-thaw cycles under uniaxial compression

To study the rock fracturing characteristics in cold-region engineering, uniaxial compression tests are conducted on double unparallel fissure-contained sandstone specimens subjected to freeze-thaw (FT) cycles. First, the effects of FT cycles on the water absorption, peak strength, initiation stress and deformation behavior of flawed sandstone specimens are investigated. The water absorption, uniaxial compressive strength, initiation stress, elastic modulus and deformation modulus of flawed sandstone specimens decrease with an increase in the number of FT cycles. However, the peak strain of flawed sandstone specimens increases with an increase in the number of FT cycles. Second, the cracking processes of flawed sandstone specimens are investigated in detail via images captured by a high-speed digital video camera system. The relationship between the real-time crack coalescence and the axial stress-strain curve of flawed specimens, which evaluates the macroscopic deformation characteristics of precracked rock subjected to FT cycles well, is considered. Third, the interaction mechanism of fissures in rock specimens is discussed. Fourth, the influence of water and temperature on the rock-weakening process is discussed. In this study, during the rock FT cycle weakening process, the effect of water, including the dissolution effect and the stress effect, is analyzed, whereas temperature damages the rock by means of different temperature gradients and the phase transition of water. Finally, the local strong fatigue-damaged zones around the fissure tips of sandstone specimens are also analyzed. These experimental results are helpful to improve the understanding of fracture mechanisms of a rock mass in cold-region engineering.

Anti-cataract Effect of Resveratrol in High-Glucose-Treated Streptozotocin-Induced Diabetic Rats.

Resveratrol, which is a polyphenol found in grapes, peanuts, and other plants, has health benefits for various chronic diseases. The aim of the present study was to examine the effect of resveratrol on cataract formation in diabetic rats. Male Wistar rats (7-week-old) were treated with streptozotocin, and the streptozotocin-treated animals were administered 5% D-glucose in drinking water to promote the formation of cataracts by inducing severe hyperglycemia. Resveratrol supplementation (10 or 30 mg/kg/d) in drinking water was initiated immediately after induction of diabetes was confirmed. The full lens images of the horizontal plane were captured with the digital camera system which we developed. Cataract formation was assessed by an observer-based scoring method and by quantitative analysis of digital images of the lens. Cataracts at the peripheral region of the lens were detected 2 weeks after induction of hyperglycemia and progressed depending on the length of the diabetic period. The majority of them developed severe cataracts after 9 weeks of hyperglycemia. Resveratrol did not prevent the appearance of diabetic cataracts but significantly delayed the progression of cataracts compared with controls. The contents of sorbitol and protein carbonyls in lenses of diabetic rats were higher than those of control rats. Resveratrol suppressed the increase in protein carbonyls, but not of sorbitol, in diabetic lenses. These results suggest that resveratrol delays the progression of diabetic cataracts partially through attenuation of oxidative damage to lens proteins. Resveratrol may be beneficial in preventing the progression of diabetic cataracts.

Measurements of Midfrequency Acoustic Backscattering From a Sandy Bottom in the South Yellow Sea of China

Acoustic bottom scattering is the main source of reverberation background in target detection and recognition near the seafloor. Accurate estimation of bottom scattering strength is necessary for prediction of sonar performance in the presence of reverberation in shallow-water environments. A measurement of bottom backscattering strength at midfrequency in a shallow-water environment of the South Yellow Sea of China was carried out in April 2016, where the water depth was 39 m. The surface of the seafloor was relatively flat and covered by some shell fragments observed through a digital camera system. Core data showed that the main component of sediment at this experiment site was fine sand. The backscattering strength as a function of grazing angle (20°–70°) in the frequency range of 6–12 kHz was extracted from monostatic backscattering data, employing an omni-directional source and an omni-directional hydrophone. The measured backscattering strength increases with the increase of the grazing angle, and changes more rapidly at large grazing angles (60°–70°). Comparing the data at different frequencies, it is found that the measured backscattering strength slightly increases with the increase of the acoustic frequency. A fit of Lambert's law to the measured data shows that the backscattering strength deviates from the Lambert's law at large grazing angles. Finally, the fitted result of a scattering model to the measured data suggests that seafloor roughness scattering is larger than that from sediment volume heterogeneity in the measurement frequency band.

TOWARDS STANDARDIZED EVALUATION OF IMAGE QUALITY FOR AIRBORNE CAMERA SYSTEMS

Abstract. Digital airborne camera systems and their high geometric resolution demand for new algorithms and procedures of image data analysis and interpretation. Parameters describing image quality are necessary for various fields of application (e.g. sensor and mission design, sensor comparison, algorithm development, in-orbit-behaviour of instruments). The effective sensor resolution is one important parameter which comprehensively estimates the optical quality of a given imaging sensor-lens combination. Although determination of resolving power is a well-studied field of research, there are still some scientific questions to be answered when it comes to a standardized (eventually absolute) determination. This is also research object of a committee of the “German Institute for Standardization” and the given contribution outlines the current state of investigation concerning effective resolving power for airborne camera systems. Therefore an approach using signal processing techniques to calculate the effective image resolution will be described. The open scientific issues will be introduced, explained and answered to some extend.

Spectral reflectance estimation of organic tissue for improved color correction of video-assisted surgery

With video-assisted surgery devices becoming more common in all fields of diagnostics and therapy, the question of how well such systems are able to reproduce surface colors of organic tissue arises, especially in cases where a proper distinction of different kinds of tissue—not only through their texture but also through their color—might be crucial for the success of a surgery. Since modern devices are usually made of a highly efficient, multispectral LED light source in combination with some light-guiding structures and a digital camera system, an approach of optimizing these systems’ color reproduction properties based on the estimation of in-situ spectral reflectances is proposed. Following the International Organization for Standardization (ISO) standard procedure of colorimetric characterization, an initial color correction matrix was determined first by solving a linear least-mean-squares optimization problem for a small set of artificial color samples mapping the corresponding camera responses onto the samples’ tristimulus values. This initial matrix was then used as a starting point for a second, nonlinear optimization, which makes use of the estimated reflectance spectra in order to minimize the average squared color difference between the color corrected and the actually perceived tristimulus values of the individual organic tissue samples. Compared to the ISO standard, which only knows simple color patches to be used for the nonlinear optimization, a significant enhancement in the color reproduction of organic tissue could be confirmed with the newly proposed method being applied instead.

Local Void Fractions and Bubble Velocity in Vertical Air-Water Two-Phase Flows Measured by Needle-Contact Capacitance Probe

Multiphase flow measurements have become increasingly important in a wide range of industrial fields. In the present study, a dual needle-contact capacitance probe was newly designed to measure local void fractions and bubble velocity in a vertical channel, which was verified by digital high-speed camera system. The theoretical analyses and experiments show that the needle-contact capacitance probe can reliably measure void fractions with the readings almost independent of temperature and salinity for the experimental conditions. In addition, the trigger-level method was chosen as the signal processing method for the void fraction measurement, with a minimum relative error of −4.59%. The bubble velocity was accurately measured within a relative error of 10%. Meanwhile, dynamic response of the dual needle-contact capacitance probe was analyzed in detail. The probe was then used to obtain raw signals for vertical pipe flow regimes, including plug flow, slug flow, churn flow, and bubbly flow. Further experiments indicate that the time series of the output signals vary as the different flow regimes and are consistent with each flow structure.

Utilization of Open Source Technology to Create Cost-Effective Microscope Camera Systems for Teaching

Background: Open source technologies and mobile innovations have radically changed the way people interact with technology. These innovations and advancements have been used across various disciplines and already have a significant impact. Microscopy, with focus on visually appealing contrasting colors for better appreciation of morphology, forms the core of the disciplines such as Pathology, microbiology, and anatomy. Here, learning happens with the aid of multi-head microscopes and digital camera systems for teaching larger groups and in organizing interactive sessions for students or faculty of other departments. Methods: The cost of the original equipment manufacturer (OEM) camera systems in bringing this useful technology at all the locations is a limiting factor. To avoid this, we have used the low-cost technologies like Raspberry Pi, Mobile high definition link and 3D printing for adapters to create portable camera systems. Results: Adopting these open source technologies enabled us to convert any binocular or trinocular microscope be connected to a projector or HD television at a fraction of the cost of the OEM camera systems with comparable quality. Conclusion: These systems, in addition to being cost-effective, have also provided the added advantage of portability, thus providing the much-needed flexibility at various teaching locations.

Immunopathological Approach for Avian Influenza Virus Detection in Brain of Laying Bird with Clinical Signs of Torticollis and Curled Toe Paralysis

Infection with avian influenza virus (AIV) in laying birds field cases often lead to clinical signs of torticollis and curled toe paralysis. Clinical signs of torticollis and curled toe paralysis is similar to the clinical signs of Newcastle disease virus infection in poultry, making it difficult for the confirmation of diagnosis of infection with both viruses. Immunopathological immunohistochemistry streptavidin-biotin (IHC SB) is an antibody-based test to detect the presence of pathogens, especially AIV in poultry with the principle of antigen detection in tissue specimens. This research aims to detect AIV infection in laying birds field case with clinical signs of torticollis and curled toe paralysis. The samples (brains from 20 layer chicken) were taken from the cases of the disease in poultry in several commercial poultry farms. The chickens showed clinical signs of torticollis and curled toe paralysis, and oedema in the brain suspected of being infected AIV. After being necropsied, then the brains were tested IHC SB and observed with a digital microscope camera system and analyzed descriptively qualitative. The results showed that the avian influenza virus antigens was found in the parenchyma, neural and endothelial cells of brain blood vessels. Based on these results, we can conclude that Immunopathologic immunohistochemical staining of streptavidin-biotin can be applied for confirmation of the diagnosis of avian influenza virus (AIV) on the brain of commercial laying chickens showing torticollis and curled toe paralysis. Keywords : AIV; IHC SB; brain; torticollis; curled toe paralysis

Automated Meteor Detection by All-Sky Digital Camera Systems

We have developed a set of methods to detect meteor light traces captured by all-sky CCD cameras. Operating at small automatic observatories (stations), these cameras create a network spread over a large territory. Image data coming from these stations are merged in one central node. Since a vast amount of data is collected by the stations in a single night, robotic storage and analysis are essential to processing. The proposed methodology is adapted to data from a network of automatic stations equipped with digital fish-eye cameras and includes data capturing, preparation, pre-processing, analysis, and finally recognition of objects in time sequences. In our experiments we utilized real observed data from two stations.

Pendekatan Diagnosis Avian Influenza Virus dan Newcastle Disease Virus pada Kasus Lapangan Ayam Petelur: Imunopatologis Streptavidin Biotin

Poultry can be infected not only by one type of virus, but also by more than one type of virus. Avian influenza virus (AIV) and Newcastle disease virus (NDV) are two important pathogens in poultry that can cause recurrent outbreaks and often lead to clinical symptoms and pathological lesions similar in poultry with high morbidity and mortality causing significant economic losses to the poultry industry. This study aims to detect and differentiate pathogenic viruses in commercial laying chickens with similar clinical symptoms, especially torticolis and curled toe paralysis, and anatomic pathological lesions, such as foci necrotic hemorrhages in the digestive tract by applying streptavidin-biotin immunohistochemical immunological test (IHC SB). Samples (chickens) were taken from the cases of the disease in poultry in several commercial poultry farms. The layer chickens in which showed clinical symptoms of torticolis and curled toe paralysis, and hemorrhagic lesions in the lungs and / or digestive system are suspected of having AIV and NDV infections. After being necropsied, then lungs and gastrointestinal tract were tested IHC SB. The IHC SB results were examined with a digital microscope camera system. The results of the present study indicated that AIV antigen was detected in the lungs, but not in the digestive tract, whereas, NDV was detected in the digestive tract, but not in the lungs. It was concluded, that the IHC SB can be applied for confirmation of the diagnosis of AIV and NDV and indicated, that the commercial laying chickens with clinical symptoms of torticolis and curled toe paralysis, as well as pathological hemorrhagic lesions in the gastrointestinal tract could be infected by both viruses.

The Use of Fibroblasts for Ameliorating Structural Changes Associated with Skin Aging.

Various causes underlie the structural changes associated with skin aging. To treat these problems, surgical or nonsurgical approaches are available. One of the nonsurgical approaches-regeneration therapy-has become the focus of research and clinical applications. In an earlier clinical study, we injected fibroblasts into the nasolabial region and lips to counter the structural changes associated with skin aging. Assessments performed 12 months after the first injection showed mostly adequate satisfaction scores. However, objective evaluation had not been performed. In the present clinical study, we injected autologous gingival fibroblasts into the nasolabial region and performed objective evaluation using a high-resolution digital camera system 12 months after the first injection. Objective evaluation showed significant improvement in moisture and grain. Subjective evaluation also demonstrated mostly satisfactory results 12 months after the first injection. According to our present results, autologous gingival fibroblast injection might be capable of ameliorating the structural changes associated with skin aging.

Improvement of star identification based on star trace in star images

Abstract Digital zenith camera system is a highly accurate positioning instrument in geodetic astronomy. It can capture 16 star images in one experiment unit in different azimuthal camera orientations and the stars in each star image should be identified using star catalogue. But the amount of calculation is very large, the efficiency of star identification is low. Now, the improvement of star identification is mainly through updating algorithm. Considering that there exist identical stars in these star images, this paper provides a new method to improve star identification. The star trace is deduced taking the earth rotation and instrument rotation into consideration. The errors of star trace are also analyzed. Then select the same stars that appear in the star images taken in the initial position and after rotating one angle. Using the identical stars instead of star catalogue and the star trace to identify the rest stars, the efficiency will get improved. The analysis of experimental data shows that there are many identical stars in these star images. The appearance of one star can be predicted according to the star trace. The star identification get improved by using the same stars in these star images. And it costs less time to identify the stars in star images, but the precision is approximately equal.

An UAS-assisted multi-sensor approach for 3D modeling and reconstruction of cultural heritage site

Abstract Unmanned Aerial System (UAS) has been widely used to produce highly-precise orthomosaics, Digital Surface Models (DSMs), Digital Terrain Models (DTMs) and 3D models in many applications. UAS is also utilized to document cultural heritage sites using low-cost photogrammetric approach. Particularly, possibility of multi-sensor acquisition provides substantial information about both geometric features and material classification. In this study, a novel methodology using multi-sensor data acquisition is proposed in order to extract and to distinguish material features from UAS-based photogrammetry for the cultural heritages. Sensors which are able to collect visible, thermal and infrared radiations of the electromagnetic spectrum were employed to produce 3D model information of Assus Ancient Theater located in Behramkale Village, Canakkale, Turkey. The results showed that the accuracies of the 3D models were obtained as ±2–3 cm, ±10–15 cm and ±5–7 cm for the digital, thermal and multi-spectral camera systems, respectively. Beside the given high-accurate geometric model, the classification outcomes as a result of the spectral analysis revealed material features in an affordable and efficient way.

Geometric Analysis of Digital Aerial Images

The data produced by photogrammetric methods have become used more effectively and efficiently to take
 place of digital aerial cameras to aerial film cameras. Digital aerial cameras have distinct properties according
 to imaging geometry, sensor numbers, the placement of camera cones and image recording techniques. Since
 2000, many studies have been done upon the geometric analysis of the rapidly developing digital imaging
 system. Intergraph DMC and Vexcel Ultracam are among the most popular digital imaging systems in this
 area. These cameras are large-format digital aerial camera systems.
 The purpose of the present study was to investigate the geometric performance of DMCII-250e and Vexcel
 UltraCamX large-format digital aerial camera systems. The test flights were performed in Bursa province. Two
 different image blocks which are 10 cm GSD and 30 cm GSD were acquired at different flight altitudes. The
 image measurements for aerial triangulation were performed by Mescioglu Engineering Inc. The images were
 processed with Match-AT software. It has been compared the residuals of coordinates and RMS of ground
 control points and check points triangulated image blocks.

High-Temporal Resolution Photography for Observing Riparian Area Use and Grazing Behavior

Observation is a simple method of acquiring information and is a critical step in the scientific method for both developing and investigating testable hypotheses. Cameras have long played a role in observation, and as technology advances, new tools and methods for collecting, interrogating, and displaying large quantities of high-resolution images have evolved. We describe an automated digital time-lapse camera system and present an example field deployment to observe the temporal and spatial patterns of riparian use by humans and animals during a 3-mo period. We also describe software tools for image interrogation and visualization, as well as new information gathered through their use. The system was tested in 2014, in a 2.4-ha site within the Apache-Sitgreaves National Forest in east central Arizona, United States where elk (Cervus elaphus nelsoni) and cattle grazed. Photographs were taken every 30 sec for 38 d, after which an electric fence was installed to restrict cattle access and the time step was increased to every 3 min. We observed that elk exhibited the unique behavior of standing in and traveling within the stream channel while grazing and tended to graze and lie in close proximity to the channel. Cattle drank from, but typically did not enter, the stream channel and tended to lie away from the channel. Recreational use by people had the distinct impact of dispersing elk from the riparian corridor. Zoomable time-lapse videos allowed us to observe that in contrast to the cattle, elk grazed while lying down. High-temporal resolution photography is a practical tool for observing phenomena that are important for local resource management.