Common Digital Camera Research Articles

Multi-View Comprehensive Graph Clustering

Multi-view clustering algorithms have been successfully used in different consumer electronic products, such as common digital cameras and unmanned vehicles. Currently, existing multi-view graph clustering (MVGC) methods learn the similarity of directly connected samples for clustering. However, these MVGC methods can not fully consider the indirect relation among samples and high-order relation across multi-view data. In this paper, a new multi-view comprehensive graph clustering (MCGC) method is devised, which can fully learn the similarity based on (1) first-order proximity (FOP) (i.e. the direct relation of pairwise samples); (2) second-order proximity (SOP) (i.e. the indirect relation of pairwise samples); and (3) third-order proximity (TOP) (i.e. the three-order relation of multiple views). Since the operations of these three components are iteratively carried out, the interaction between similarity learning can be encouraged and the comprehensive graph can be generated effectively for clustering. In-depth experiments on six commonly benchmark datasets show the superiority of the MCGC method.

Preprocessing of Crack Recognition: Automatic Crack-Location Method Based on Deep Learning

With advancements in artificial intelligence and computer vision, machine learning has become widely employed in location and detection of road pavement distresses. Recently, recognition methods based on convolutional neural networks (CNNs) have been implemented to segment pavement cracks at pixel level in order to evaluate the pavement condition. However, this method usually consists of some common processes, including manually predetermining the approximate location of cracks followed by selecting the image containing the cracks and then performing pixel-level segmentation, which is why it is worth automating the preprocessing to replace the manual selection step. Moreover, the issues of a low proportion of positive samples, complex crack topologies, different inset conditions, and complex pavement background make the task of automatic pavement location more challenging. Therefore, this paper proposes a novel method for preprocessing crack recognition, which automatically locates cracks and yields great savings in labor costs. Specifically, a real-world road pavement crack data set obtained from a common digital camera mounted on a vehicle is built to test the proposed crack location method, called Double-Head. It improves the accuracy of crack object localization by using an independent fully connected head (fc-head) and a convolution head (conv-head). The results show that our method improves average precision (AP) 6.5% over Faster R-CNN using only a fc-head, and outperforms many advanced object detection methods.

Noninvasive identification of Benign and malignant eyelid tumors using clinical images via deep learning system

Eyelid tumors accounts for 5–10% of skin tumors. It is important but difficult to identify malignant eyelid tumors from benign lesions in a cost-effective way. Traditional screening methods for malignancy in eyelid tumors require laborious and time-consuming histopathological process. Therefore, we aimed to develop a deep learning (DL)-based image analysis system for automatic identification of benign and malignant eyelid tumors. Using a common digital camera, we collected clinical images from patients who were histopathologically diagnosed with eyelid tumors. We trained 8 convolutional neural network (CNN) models to identify benign and malignant eyelid tumors, including ResNet-50, ResNet-101, InceptionV3, and InceptionResNetV2. Another group of patients with eyelid tumors were also collected as the prospective validation dataset. Performance of DL models and human clinicians in prospective validation dataset were evaluated and compared. A total of 309 images from 209 patients were used for training DL system, all eight models reached an average accuracy greater than 0.958 in the internal cross-validation. 36 images from 36 patients were included for the prospective validation, the models reached the best performance in accuracy, sensitivity, specificity, and area under curve (AUC) of 0.889 (95% CI 0.747–0.956), 0.933 (95% CI 0.702–0.988), 0.857 (95% CI 0.654–0.950), and 0.966 (95% CI 0.850–0.993), respectively. DL system had a similar performance as the senior ophthalmologists, and outreached the performance of junior ophthalmologists and medical students. DL system can identify benign and malignant tumors through common clinical images, with a better performance than most ophthalmologists. Combining DL system with smartphone may enable patients’ self-monitoring for eyelid tumors and assist in doctors’ clinical decision making.

Evaluation of the hygroexpansion of Japanese papers by digital image correlation (3D-DIC) and application to the study of the impact of inlay mounting on the strain of an albumen photographic print

• Inlay-mounted albumen photographic prints become cockled during exhibition. • The mass and the in-plane and out-of-plane displacement of different papers were evaluated by DVS and 3D-DIC as the humidity fluctuated. • The Japanese papers tested have lower strain than the Western paper and, for some samples, very similar hygroexpansion in the machine and cross-machine direction. • The differences in hygroexpansion of the materials may explain the formation of cockles. • DIC can assist in the decision-making process when selecting materials and techniques for conservation treatment. During an exhibition of photographs, a temporary excess of humidity caused waviness to form on some inlay-mounted albumen prints, which persisted and required conservation treatment. In order to understand the origin of this phenomenon, dynamic water sorption (DVS) measurement and digital image correlation (DIC) have been applied to assess the weight and the mechanical behavior of the materials when the humidity varies. The 3D-DIC has been performed using common digital cameras and commercial software. The in-plane hygroexpansion and out-of-plane displacements of various paper samples and of a 19 th -century albumen photographic print, subjected to humidity fluctuation, made it possible to explain the origin and the persistence of waviness of the photograph in an inlay mount. This non-contact and multi-scale technique is therefore particularly useful for assessing the mechanical behavior of cultural heritage materials. It permitted the evaluation of the compatibility or incompatibility between materials depending on the climatic conditions, whether from the point of view of in-plane or out-of-plane displacements, and enabled potential risks linked to thermo-hygrometric variations to be foreseen.

Electrogenerated chemiluminescence of luminol on wireless conducting polymer films

We report on the generation of electrochemiluminescence (ECL) from luminol and hydrogen peroxide (H2O2) in alkaline aqueous solution on entirely pure conducting polymer (CP) films. Poly(3,4-ethylenedioxythiophene) (PEDOT) and polypyrrole (PPy) films prepared by constant current electrolysis were used as bipolar electrodes (BPEs) to drive ECL emission in a wireless mode with the aid of bipolar electrochemistry. A common digital camera was used to capture the strong ECL emission of luminol generated at the anodic pole of such films. ECL intensity profiles revealed a gradient emission on both materials, with a broad light-emitting region on PPy and a narrow, edge-confined, ECL region on PEDOT. Imaging analysis also allowed the evaluation of the ECL behavior of both CPs as a function of the total applied voltage (Etot) and conductivity. Furthermore, electric-field driven generation of molecular O2 induces propulsion of PEDOT and PPy films that can be followed by luminol ECL. In our knowledge, such result represents the first example of light-emitting electrochemical swimmers based on free-standing films of intrinsically pure CPs. We presume that our findings can both foster the use of such materials in the wide fields of ECL and bipolar electrochemistry and open up to their application as organic light-emitting electrochemical swimmers.

Ultra-flexible and highly sensitive scintillation screen based on perovskite quantum dots for non-flat objects X-ray imaging

A flexible and highly sensitive scintillation screen is urgently expected for X-ray imaging technology, especially for non-flat, flexible objects in medical and industrial applications. Here, we report a sandwich structure of polymer-perovskite quantum dots-polymer (PPP) scintillation screen. The outer polymer layer provides high mechanical stability and encapsulation for the internal perovskite quantum dots active layer. The relative light output remains 93 ± 0.5% of its initial value after bending cycles up to 600 with a bending radius down to 2.5 mm. This PPP scintillation screen exhibits ultra-sensitivity to low energy X-ray with a detection limit of 1.57nGyair/s and fast decay time of 63.7ns. Well-resolved X-ray images are recorded with a common digital camera with a spatial resolution of 5.35 lp/mm at MTF = 0.3 under the exposure dose of 12 μGyair, which is much lower than the requirement of medical applications. These features demonstrate that this flexible scintillation screen can be applied for non-flat X-ray imaging applications under low-dose X-ray exposure.

Enhanced characterization of the yield behavior of sheet metal at torsional load using digital image correlation methods

This work describes an approach for strain determination at the “in-plane” torsional test using digital image correlation (DIC) without brushing a statistical pattern on the specimen. It is well known that the in-plane torsion test represents a appropriate test method for material characterization of sheet metal in terms of yielding and kinematic hardening (Wagner et al. in Application of the in-plane torsion test in an industrial environment—recent advances and remaining challenges. In: Conference Paper of the 12th Forming Technology Forum, Herrsching, Germany, 2019). However, the gained measurement data do not allow the exact reading of material models for direct use in numerical analysis. The determination of shear values represents thereby the main challenge. Besides well-established methods for stress–strain analysis mentioned in this contribution, the applicability of DIC methods for the direct reading of distortion on the specimen has been investigated. Therefore, a torsion test rig has been developed and torsion tests using specimen out of mild- and high-strength steel have been conducted. The in-plane situation allows the distortion tracking of single points on the specimen by using a 2D image correlation software. The needed pictures were taken by using a common digital lens reflex camera. It has been shown that the resolution of the inherent specimen pattern is sufficient for the use of common 2D image correlation software. Torsional test results in the form of computed yield curves of mild- and advanced high-strength steels are aimed to be presented in this contribution.

Tracking down chemical phenomena with the usage of mobile phone slow-motion videos

Abstract Some experiments in chemistry occur too fast to make out the central phenomena. Using common digital cameras or mobile phones with high-speed options, one can slow down the process and make the vital observations visible and capable for the students. This article introduces the research project SloMoChem and will show the benefits of using this digital technology to understand the combustion concept in a much better way.

Application of DIC Method in the Analysis of Stress Concentration and Plastic Zone Development Problems.

The paper presents the assessment of the possibility and reliability of the digital image correlation (DIC) system for engineering and scientific purposes. The studies were performed with the use of samples made of the three different materials—mild S235JR + N steel, microalloyed fine-grain S355MC steel, and high strength 41Cr4 steel subjected to different heat-treatment. The DIC studies were focused on determinations of dangerous zones with large stress concentrations, plastic deformation growth, and prediction of the failure zone. Experimental tests were carried out for samples with different notches (circular, square, and triangular openings). With the use of the DIC system and microstructure analyses, the influence of different factors (laser cutting, heat treatment, material type, notch shape, and manufacturing quality) on the material behavior were studied. For all studied cases, the stress concentration factors (SCF) were estimated with the use of the analytical formulation and the finite element analysis. It was observed that the theoretical models for calculations of the influence of the typical notches may result in not proper values of SCFs. Finally, the selected results of the total strain distributions were compared with FEM results, and good agreement was observed. All these allow the authors to conclude that the application of DIC with a common digital camera can be effectively applied for the analysis of the evolution of plastic zones and the damage detection for mild high-strength steels, as well as those normalized and quenched and tempered at higher temperatures.

Mix-and-read method for assessment of milk pasteurization using a smartphone or a common digital camera.

Alkaline phosphatase (ALP) is the most widely used marker of the adequacy of milk pasteurization since it is inactivated at temperatures slightly higher than those required for elimination of pathogens. The cutoff level is 350mU/L. The approved colorimetric, fluorometric, and chemiluminometric methods require specialized readers with photomultipliers as detectors, and the samples are usually analyzed one-by-one. We developed a low-cost mix-and-read method that exploited a smartphone or a common digital camera as detectors for the chemiluminometric determination of ALP in milk. As samples, we used pasteurized cow and sheep milk spiked with ALP, as well as mixtures of pasteurized and raw (non-pasteurized) milk. Chemiluminescence images acquired by the smartphone or the digital camera were analyzed by the ImageJ software. The limits of detection (LODs), for images captured by the smartphone, were 4.4mU/L and 11.1mU/L for cow milk and sheep milk, respectively, while with the digital camera, the respective LODs were 6.2mU/L and 6.7mU/L, respectively. The coefficients of variation (CVs) at the cutoff level of 350mU/L were 8% and 8.5% for the cow and sheep milk, respectively. For images by the digital camera, the CVs were 5.8% and 5% for cow and sheep milk, respectively. The performance of the method is similar to methods that use a microtiter plate and a luminometer for chemiluminescence measurements. Sample pretreatment is not necessary. The microtiter well format combined with detection by a smartphone enables the analysis of multiple samples simultaneously. It is anticipated that the method will prove useful for the rapid assessment of milk pasteurization efficiency in dairy industries, especially in remote areas where expensive instruments are not available. Graphical abstract.

Two-dimensional Fourier domain Ronchi ruling measurement using Talbot-based crossing point modeling

We propose a direct two-dimensional Fourier domain fitting-free method to determine the period of a Ronchi ruling. A precise method to measure a spatial frequency target’s quality and fidelity is highly desired as the pattern period directly affects every aspect of a spatial frequency target-based metrology, including the accuracy and precision of the measurement or evaluations. A standard Talbot experimental apparatus and the Talbot effect are used to obtain and model our data. To determine the period of the ruling directly, only a common digital camera, with a protective glass and an air gap in front of the sensor array, and a Ronchi ruling of chrome deposited on a glass substrate are required. The Talbot effect-based crossing point modeling technique requires no calibration or a priori information but simply the pixel size of the digital camera and a precise means of measuring the spatial frequency from a Talbot image. For a Ronchi ruling with a period specification of 0.1 mm, the nanometric measurement was found to be 0.100010 mm with an error level of 5 nm.

Three-dimensional image-based approach for imperfect structures surface modeling

Great attention has been given, in the scientific literature, to the effect of initial imperfections on the structural behavior of experimental samples under compression loads. Geometrical reconstruction of the as-built surface is therefore required to allow accurate numerical modeling. High-precision systems for inverse engineering are expensive, and most of the times geometrical imperfections are rather complex to be described without high computational efforts. In this paper, an image-based approach to model the surface of imperfect structures using open-source software and a common digital camera is presented. The proposed approach aims to generate high-quality surfaces from real imperfect structures, by employing the surface-from-motion and multi-view stereo techniques. A controlled frame capture is introduced to decrease both the computational effort and number of repeated correspondences. The surface fit is then computed by meshing the dense cloud of points and adjusting several surface regions describing the samples’ profiles. The procedure is illustrated by using two damaged tubular member samples reconstructed by the proposed approach. Then, resulted geometries are verified by comparing measures from a three-dimensional high-precision laser scanner and a common mechanical procedure. Finally, a comparison of three-dimensional mappings of a ship panel with proposed approach and commercial photogrammetry software is performed. Verification results refer to the possibility of prototyping geometry surfaces from real imperfect samples by using inexpensive hardware and public domain software tools with acceptable level of accuracy.

Preparation and adsorption performance evaluation of activated carbon fibers derived from rayon

Activated carbon fiber (ACF) is a material that has attracted significant attention because ACFs derived from several fiber sources have been adapted as filter materials. Here, we described successful ACF preparation via single- and two-step thermal treatments of rayon. Methylene blue adsorption abilities of the resulting ACFs were evaluated. Results indicated that ACFs derived from rayon which is prepared by the two-step thermal treatment demonstrate adsorption ability. Moreover, the average gray-scale intensities (GIs) of the carbonized samples were obtained from images captured with a common digital camera, and the results exhibited meaningful correlations for both yield and absorption ability with GI. Correlation between GI and absorption ability suggests the potential for a simple, nondestructive method of evaluating the absorption ability of ACFs. Results obtained for rayon is easily transferred to other fiber products or industrial waste materials generated during the manufacture of textiles that offers potential energy savings.

The Finger-Based Interactive Projection using a Monocular Camera

Ordinary projection screen is not sensitive to interaction, it cannot meet the demands of teaching, virtual reality, and other applications. Due to the fact that people always use hands to complete a variety of human–computer interaction, the finger-based interactive projection technology is worth being researched. In this paper, an ordinary monocular camera is used to acquire video frame on projection screen, and the touch signal of finger in frame is used as the input of interactive projection system. Because the differences between spatial frequency of common digital camera and the projection screen is small, the frame obtained from camera will contain moire fringe, which needs to be filtered in image frequency domain. Then the difference between current frame edge and previous frame edge is calculated to obtain moving object edge clues. According to these clues, the most possible contour curve is searched in current frame edge, and the curve is fitted by polynomial approximation method. Its curvature integration is used to match with the curvature integration of finger template curve. After that the fingers in the curve are recognized. Because color information is not needed, this method can be used to recognize gloved fingers. Finally, finger shadow is used to judge whether the finger touches projection screen to complete interactive process. The experiments of writing and collaboratively rotating picture on projector screen show that this method can effectively complete interactive operation with the projection screen and can realize the multi-user operation.

Direct instantaneous 2-D imaging for photoacoustic waves by ultrashort single pulse interferometry

We perform ultrafast optical imaging by means of single pulse interferometry (SPI) using sub-picosecond ultrashort laser pulses. Laser-induced photoacoustic waves propagating at the sonic speed are captured in 2-D instantly without time-consuming area scanning or averaging-out of electronic noise. A common digital camera offering merely a millisecond-scale exposure is employed in synchronization with pulse picking so as to receive only a single pulse per camera frame. High fringe visibility is obtained with low background noise by blocking asynchronous spontaneous emission (ASE) mixed in source pulses by second harmonic filtering. Our proof-of-concept experimental scheme permits a 0.25 ps effective exposure time with almost ideal image contrast by optical coherence pulse gating. The 2-D ultrafast imaging capability is evaluated through a pump-probe measurement of a 60.8 MHz laser-induced photoacoustic wave in liquid.

Exposure Fusion for Dynamic Scenes Combining Retinex Theory and Low-Rank Matrix Completion

Exposure fusion (EF) directly generates a low dynamic range (LDR) image with similar image quality to the high dynamic range (HDR) image by combining images of different exposures to overcome the limited dynamic range of common digital cameras. EF for dynamic scenes is challenging not only due to the difficulty in removing various ghost artifacts but also because of the requirement of preserving details, especially in the saturated regions. Recently, low-rank (LR) matrix completion (LRMC) has been shown to be efficient in separating the latent background from the sparse motion in the irradiance domain. However, the performance of LRMC models strongly relies on the estimated irradiance images. To address this problem, this paper proposes a novel EF method combining Retinex theory and the LRMC model. The proposed method consists of four steps. First, according to Retinex theory, an image is decomposed into illumination and reflection components. Second, the LRMC model is applied to the reflection component to generate the background reflection component and the sparse error. Third, the motion map is modeled as a Markov random field (MRF), integrating the sparse error with the ordering constraint across all the illumination components. Finally, all the illumination components are fused via a pyramid-based method, where the weight maps are defined based on the obtained motion map and illumination. The experimental results show that the proposed method outperforms the state-of-the-art methods particularly in preserving details in saturated regions.

A fluorometric lateral flow assay for visual detection of nucleic acids using a digital camera readout.

A fluorometric lateral flow assay has been developed for the detection of nucleic acids. The fluorophores phycoerythrin (PE) and fluorescein isothiocyanate (FITC) were used as labels, while a common digital camera and a colored vinyl-sheet, acting as a cut-off optical filter, are used for fluorescence imaging. After DNA amplification by polymerase chain reaction (PCR), the biotinylated PCR product is hybridized to its complementary probe that carries a poly(dA) tail at 3΄ edge and then applied to the lateral flow strip. The hybrids are captured to the test zone of the strip by immobilized poly(dT) sequences and detected by streptavidin-fluorescein and streptavidin-phycoerythrin conjugates, through streptavidin-biotin interaction. The assay is widely applicable, simple, cost-effective, and offers a large multiplexing potential. Its performance is comparable to assays based on the use of streptavidin-gold nanoparticles conjugates. As low as 7.8 fmol of a ssDNA and 12.5 fmol of an amplified dsDNA target were detectable. Graphical abstract Schematic presentation of a fluorometric lateral flow assay based on fluorescein and phycoerythrin fluorescent labels for the detection of single-stranded (ssDNA) and double-stranded DNA (dsDNA) sequences and using a digital camera readout. SA: streptavidin, BSA: Bovine Serum Albumin, B: biotin, FITC: fluorescein isothiocyanate, PE: phycoerythrin, TZ: test zone, CZ: control zone.

Estimating the size of plants by using two parallel views

AbstractThis paper presents a method of estimating the size of plants by using two parallel views of the scene, taken by a common digital camera. The approach relays on the principle of similar triangles with the following constraints: the resolution of the camera is known; the object is always in parallel to the camera sensor and the intermediate distance between the two concessive images is available. The approach was first calibrated and tested using one artificial object in a controlled environment. After that real examples were taken from agriculture, where we measured the distance and the size of a vine plant, apple and pear tree. By comparing the calculated values to measured values, we concluded that the average absolute error in distance was 0.11 m or around 3.7 %, and the absolute error in high was 0.09 m or 4.6 %.

Bundle block adjustment of large-scale remote sensing data with Block-based Sparse Matrix Compression combined with Preconditioned Conjugate Gradient

In recent years, new platforms and sensors in photogrammetry, remote sensing and computer vision areas have become available, such as Unmanned Aircraft Vehicles (UAV), oblique camera systems, common digital cameras and even mobile phone cameras. Images collected by all these kinds of sensors could be used as remote sensing data sources. These sensors can obtain large-scale remote sensing data which consist of a great number of images. Bundle block adjustment of large-scale data with conventional algorithm is very time and space (memory) consuming due to the super large normal matrix arising from large-scale data. In this paper, an efficient Block-based Sparse Matrix Compression (BSMC) method combined with the Preconditioned Conjugate Gradient (PCG) algorithm is chosen to develop a stable and efficient bundle block adjustment system in order to deal with the large-scale remote sensing data. The main contribution of this work is the BSMC-based PCG algorithm which is more efficient in time and memory than the traditional algorithm without compromising the accuracy. Totally 8 datasets of real data are used to test our proposed method. Preliminary results have shown that the BSMC method can efficiently decrease the time and memory requirement of large-scale data.

Colorimetric Detection of Alkaline Phosphatase on Microfluidic Paper-based Analysis Devices

Abstract A low-cost, simple and sensitive colorimetric detection method for alkaline phosphatase (ALP) was developed on microfluidic paper-based analysis devices. In a typical colorimetric detection, 5-bromo-4-chloro-3-indolyl phosphate disodium salt (BCIP) and nitro blue tetrazolium (NBT) were firstly added onto the circle array zones of paper devices. Then ALP solutions were spotted to the array zones to perform the colorimetric reaction. The color reaction results were recorded by both Gel Documentation systems and a common digital camera, and analyzed with Quantity One software. All the reaction conditions were optimized. Under the optimal conditions, the colorimetric intensity showed a linear correlation to the concentration of ALP in the range of 1.5–20 U L −1 with a limit of detection (LOD) of 0.78 U L −1 (3σ), which was about two orders of magnitude lower than that of the reported method on µPADs. Besides, it was applied in the analysis of spiked real sample with a satisfactory result. In addition, the dual-color array-based paper strip was fabricated for the semiquantitative detection of ALP. The approximate activity of ALP could be simply distinguished by the color change with naked eyes.