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Underwater imaging is receiving attentions throughout these years. Attenuation of light causes the underwater images to have poor contrast and deteriorated color. Furthermore, these images usually appear foggy and hazy. In this paper, a new approach to enhance underwater images is proposed, which implements the integration of dehazing method, homomorphic filtering and image fusion. The dehazing method consists of multi-scale fusion technique, which applies weight maps in the pre-processing step. Homomorphic filtering and image fusion are then applied to the resultant image for contrast and color enhancement. Qualitative and quantitative evaluations are performed to analyze the performance of the proposed method. The results show the superiority of the proposed method in terms of contrast, image details, colors, and entropy. Moreover, implementation of Raspberry Pi with Picamera as standalone underwater image processing device is also successfully implemented.

X-ray dark-field imaging (XDFI) utilizing a thin silicon crystal under Laue case enables visualizing three-dimensional (3D) morphological alterations of human tissue. XDFI uses refraction-contrast derived from phase shift rather than absorption as the main X-ray image contrast source to render 2D and 3D images of tissue specimens in unprecedented detail. The unique features of XDFI are its extremely high sensitivity (approximately 1000:1 compared to absorption for soft tissues under X-ray energy of around 20 keV, theoretically) and excellent resolution (8.5 μm) without requiring contrast medium or staining. Thus, XDFI-computed tomography can generate 3D virtual histological images equivalent to those of stained histological sections pathologists observe under low-power light microscopy as far as organs and tissues selected as samples in preliminary studies. This paper reviews the fundamental principles and the potential of XDFI, describes two optical setups for XDFI with examples, illustrates features of XDFI that are salient for histopathology, and presents XDFI examples of refraction-contrast images of atherosclerotic plaques, musculoskeletal tissue, neuronal tissue, and breast cancer specimens. Availability of this X-ray imaging in routine histopathological evaluations of tissue specimens would help guide clinical decision making by highlighting suspicious areas in unstained, thick sections for further sampling and analysis using conventional histopathological techniques. XDFI is a promising tool for 3D virtual histopathology.

When judging optical properties of a translucent object, humans often look at sharp geometric features such as edges and thin parts. Analysis of the physics of light transport shows that these sharp geometries are necessary for scientific imaging systems to be able to accurately measure the underlying material optical properties. In this paper, we examine whether human perception of translucency is likewise affected by the presence of sharp geometry, by confounding our perceptual inferences about an object’s optical properties. We employ physically accurate simulations to create visual stimuli of translucent materials with varying shapes and optical properties under different illuminations. We then use these stimuli in psychophysical experiments, where human observers are asked to match an image of a target object by adjusting the material parameters of a match object with different geometric sharpness, lighting geometry, and 3D geometry. We find that the level of geometric sharpness significantly affects perceived translucency by the observers. These findings generalize across a few illuminations and object shapes. Our results suggest that the perceived translucency of an object depends on both the underlying material optical parameters and 3D shape. We also conduct analyses using computational metrics including (luminance-normalized) L2, structural similarity index (SSIM), and Michelson contrast. We find that these image metrics cannot predict perceptual results, suggesting low level image cues are not sufficient to explain our results.

This study is part of a larger attempt to explore how the brain produces conscious experience. Our main objective here was to take advantage of a neural signature conveyed by the steady-state visual evoked potentials (SSVEP) technique (1) to explore the extent to which complex visual images can be processed in the absence of consciousness and (2) to determine whether this tool can be used to shed light on participants’ phenomenal experience of these images. To this end, we embedded faces within sequences of non-face stimuli and manipulated their contrast to create a subliminal condition. Our results were threefold. First, we show that a significant brain activation can be delineated with the SSVEP tool even when participants report being unable to see the stimuli. In this subliminal condition, the brain response was confined to the back of the scalp. Second, we observe that the face signal increases in magnitude and propagates bilaterally along a posterior-to-anterior axis as image contrast increases. Third, we suggest that SSVEP could be used as a novel instance of a no-report paradigm because it requires no overt behavioural response, and because at some contrast levels and electrodes, its outputs (signal magnitude and scalp topography) predict people’s self-reported phenomenal experience.

The article is devoted to studying of the images synthesized by Generative Adversarial Networks (GAN). The investigated networks are stimulated with the noise-like vectors of random samples fed into their inputs. The influence of changes of input noise parameters upon the properties of synthesized images is of primary interest in this research.

Contrast enhancement is an important pre-processing task in any Image Analysis (IA) system. In this paper, we formulate the image contrast enhancement problem as an optimization problem where the goal is to optimize the pixel intensity values of an input image to obtain a contrast enhanced version of the same. This optimization task is executed by suitably customizing a nature-inspired optimization algorithm called Selfish Herd Optimizer (SHO). The optimization problem is solved using two different solution representations: pixel wise optimization (SHO(direct)) and transformation function based optimization (SHO(transformation)). Moreover, an ablation study is performed to select the most appropriate parameters which can be used in tness measure for this optimization problem. On experimenting over the popular Kodak image dataset, it has been observed that the proposed methods outperform many existing methods published recently. Further comparisons indicate that the direct approach performs better than its transformation counterpart. This paper further investigates the robustness of SHO(direct) approach by applying it to enhance the degraded document images of H-DIBCO 2018.

It is known that a spatially partially coherent light field produces better imaging contrast compared to a spatially coherent field and that the contrast increases as the spatial coherence length of the field becomes smaller. The transverse spatial coherence length of most spatially partially coherent fields increases upon propagation. As a result, the field produces progressively decreasing image quality at subsequent transverse planes. By controlling the propagation of spatial coherence, we demonstrate enhanced image quality at different transverse planes along the propagation direction through a scattering medium. Using a source with propagation-invariant spatial coherence function, we report experimental observations of imaging different transverse planes with equal contrast over a significant distance. Furthermore, we generate a spatially partially coherent source that can be tailored to have minimum-possible transverse coherence area at the plane of the object to be imaged, and using this source, we demonstrate imaging spatially separated transverse planes with maximum possible image contrast.

Advances in technology and nanomedicine have led to the development of nanoparticles that can be activated for multimodal imaging of cancer, where a stimulus induces a material modification that enhances image contrast. Multimodal imaging using nanomaterials with this capability can further combine the advantages and overcome the limitations of any single imaging modality. When designed with stimuli-responsive abilities, the target-to-background ratio of multimodal imaging nanoprobes increases because specific molecular targets in the tumor enhance the signal. Several aspects of the tumor microenvironment can be exploited as an internal stimulus response for multimodal imaging applications, such as the pH gradient, redox processes, overproduction of various enzymes, or combinations of these. In this review, design strategies are discussed and an overview of the recent developments of internally responsive multimodal nanomaterials is provided. Properly implementing this approach improves noninvasive cancer diagnosis and staging as well as provides a method to monitor drug delivery and treatment response.

Gastrointestinal disorders caused by ingestion of (oo)cysts of Cryptosporodium and Giardia is one of the major health problems in developing countries. We developed a smartphone based microscopic assay method to screen (oo)cysts of Cryptosporodium and Giardia contamination in vegetable and water samples. We used sapphire ball lens as the major imaging element to modify a smartphone as a microscope. Imaging parameters such as field of view and magnification, and image contrast under different staining and illumination conditions were measured. The smartphone microscope method consisting of ball lens of 1 mm diameter, white LED as illumination source and Lugols’s iodine staining provided magnification and contrast capable of distinguishing (oo)cysts of Crypstopsporodium and Giardia in the same sample. The analytical performance of the method was tested by spike recovery experiments. The spiking recovery experiments performed on cabbage, carrot, cucumber, radish, tomatoes, and water resulted 26.8±10.3, 40.1±8.5, 44.4±7.3, 47.6±11.3, 49.2 ±10.9, and 30.2±7.9% recovery for Cryptosporodium, respectively and 10.2±4.0, 14.1±7.3, 24.2±12.1, 23.2±13.7, 17.1±13.9, and 37.6±2.4 % recovery for Giardia, respectively. These recovery results were found to be similar when compared with the commercial brightfield and fluorescence microscopes. We tested the smartphone microscope system for detecting (oo)cysts on 7 types of vegetable (n=196) and river water (n=18) samples. Forty two percent vegetable and thirty-nine percent water samples were found to be contaminated with Cryptosporodium oocyst. Similarly, thirty one percent vegetable and thirty three percent water samples were contaminated with Giardia cyst. This study showed that the developed method can be a cheaper alternative for simultaneous detection of (oo)cysts in vegetable and water samples.

В работе рассмотрена задача контроля размаха вибрационных перемещений. Большинство технологических процессов сопровождается нежелательными вибрациями. Их наличие оказывает негативное влияние на оборудование, сооружения, объект обработки. Превышение допустимого размаха вибраций может приводить к поломкам и даже авариям. В этой связи задача контроля параметров вибрации является актуальной. Цель работы исследование погрешности измерения размаха вибрации по изменению контраста в парных штрихах. В статье приводится описание экспериментальной установки, использованной для оценки погрешности известного метода оптического контроля размаха вибрации при использовании различных тест-объектов и параметров виброперемещений. Представлены результаты экспериментального исследования. Выполнено теоретическое исследование полученных результатов. На основании него сформулированы пути минимизации погрешности измерения размаха вибрации. Исследуемые в работе методы контроля апробированы авторами ранее., The paper considers the problem of controlling the scope of vibration movements. Most technological processes are accompanied by unwanted vibrations. Their presence has a negative impact on equipment, structures, and processing facilities. Exceeding the permissible vibration range can lead to breakdowns and even accidents. In this regard, the task of monitoring vibration parameters is relevant. The purpose of this work is to study the error of measuring the vibration range by changing the contrast in paired strokes. The article describes an experimental setup used to estimate the error of the known method of optical control of the vibration span when using various test objects and vibration displacement parameters. The results of an experimental study are presented. A theoretical study of the results ob-tained was performed. Based on it, ways to minimize the error of measuring the vibration span are formulated. The control methods studied in this work were tested by the authors earlier., №4 (2020)

Water-soluble, nano-sized crosslinked polymer networks, or nanogels, are delivery vehicles, which have highly interesting properties for therapeutic delivery and imaging. Nanogels may also possess responsive properties, depending on the employed polymers, allowing controlled release of therapeutics or image contrast generation upon exposure to physical or (bio) chemical cues. In this review, polymer nanogels are explored for application in imaging as well as for controlled drug and gene delivery. Moreover, nanogels are explored as responsive biomaterials and future applications are highlighted.

OBJECTIVE. The long scan time of brain MRI is a major drawback that limits its clinical use for evaluating pediatric patients who are inherently prone to motion and frequently require sedatives. This study investigated the clinical feasibility of a 1-minute ultrafast brain MRI protocol in pediatric patients by assessing its image quality in comparison with that of routine brain MRI. MATERIALS AND METHODS. Twenty-three patients were enrolled who underwent 1-minute ultrafast MRI and routine brain MRI protocols including five essential sequences (T1-weighted imaging, T2-weighted imaging, DWI, FLAIR, and T2*-weighted imaging). Total scan time for the same image contrast levels was 1 minute 11 seconds for ultrafast MRI versus 9 minutes 51 seconds for routine brain MRI. Two readers independently reviewed all images from the two MRI protocols and graded the image quality on a 4-point Likert scale. The Wilcoxon signed rank test was used to compare the readers' ratings; interobserver agreement between the readers was also assessed. RESULTS. Although the mean scores of overall image quality and anatomic delineation in ultrafast brain MR images were significantly lower than those in routine brain MR images, ultrafast brain MRI showed sufficient overall image quality and anatomic delineation with more than 2 points on the 4-point scale. CONCLUSION. The 1-minute ultrafast brain MRI protocol showed at least sufficient image quality compared with routine brain MRI. Therefore, 1-minute ultrafast brain MRI can be a viable first-line neuroimaging study for pediatric patients because of its shorter scan time, absence of radiation hazard, and reduced sedation requirements.

Dynamic contrast-enhanced magnetic imaging (DCE-MRI) is a useful method for detection and diagnosis of liver lesions. However, DCE-MRI using Gd-EOB-DTPA has some problems with arterial phase images. Radial volumetric imaging breath-holding examination (r-VIBE) with k-space weighted image contrast reconstruction (KWIC), which is a modification of Cartesian VIBE (c-VIBE), is a new 3D-gradient echo sequence with a number of advantages compared with c-VIBE, including lower motion sensitivity. This study was performed to evaluate image contrast, blurring, and temporal phase division effects of r-VIBE in comparison with c-VIBE. Image contrast using diluted Gd-EOB-DTPA aqueous solution showed no significant difference between r-VIBE and c-VIBE. Imaging was performed with r-VIBE and c-VIBE during injection of a Gd-EOB-DTPA solution into a serpentine tube. r-VIBE showed a smaller half-width of the signal intensity profile of the tube and less image artifacts by blurring when compared to c-VIBE. The arrival times and durations of the maximum signal strengths of r-VIBE and c-VIBE images during injection of Gd-EOB-DTPA solution into the tube were almost identical. r-VIBE improved the temporal resolution without degradation of liver DCE-MRI using Gd-EOB-DTPA.

Stimulated Raman Scattering (SRS) microscopy is a powerful nonlinear optical microscopy technique that images biological structures by exploiting the characteristic, vibrational contrast of the sample molecules. SRS provides a rich, chemically specific and biophysical image contrast that is in many ways complementary to the molecular contrast of fluorescence microscopy. Here, we present a range of applications of SRS, including label-free morphochemical imaging in model organisms, the characterization of organoids and spheroids, and investigations of brain tissues for neurodegenerative disease research. We show specifically that SRS can provide novel insights into the biophysical properties and biochemical composition of Amyloid-β plaques in a mouse model of Alzheimer’s disease. Our results highlight the potential of SRS to contribute to a deeper understanding of cell and tissue biology, and to serve as a powerful tool for preclinical and translational research.

Images in bad weather can be degraded by scattering atmospheric particles, and suffer from low contrast and faint color. Main focus of this work is on dehazing methods that can be used for low-light and low-contrast conditions. Dehazing algorithms can be applied to low-light (night) imaging in a way that inverted night images are considered as hazy images. Different image quality metrics are used to measure quality of image enhancement algorithm. Since it is not easy to obtain original image without haze, special attention is given to the no-reference metrics that evaluate image contrast enhancement.

In large population studies such as the UK Biobank (UKBB), quality control of the acquired images by visual assessment is unfeasible. In this paper, we apply a recently developed fully-automated quality control pipeline for cardiac MR (CMR) images to the first 19,265 short-axis (SA) cine stacks from the UKBB. We present the results for the three estimated quality metrics (heart coverage, inter-slice motion and image contrast in the cardiac region) as well as their potential associations with factors including acquisition details and subject-related phenotypes. Up to 14.2% of the analysed SA stacks had sub-optimal coverage (i.e. missing basal and/or apical slices), however most of them were limited to the first year of acquisition. Up to 16% of the stacks were affected by noticeable inter-slice motion (i.e. average inter-slice misalignment greater than 3.4 mm). Inter-slice motion was positively correlated with weight and body surface area. Only 2.1% of the stacks had an average end-diastolic cardiac image contrast below 30% of the dynamic range. These findings will be highly valuable for both the scientists involved in UKBB CMR acquisition and for the ones who use the dataset for research purposes.

Objectives: To access the influence of the addition of a lead foil to intraoral digital radiographic receptors on image contrast and approximal caries lesions diagnosis. Methods: 40 posterior teeth were distributed in silicone phantoms composed of two premolars, two molars and a non-test canine. Radiographic images of the phantoms were obtained with and without the incorporation of a lead foil, using the Digora Optime and Digora Toto systems. Four observers scored the images for the presence of caries lesions, using a 5-point scale. Images of an aluminum step wedge were acquired with and without the incorporation of a lead foil. Gray values and standard deviation of gray values were calculated in different thickness of the step wedge and, then, contrast variation was calculated. Results: Presence of a lead foil did not influence caries lesions diagnostic values, regardless of the type of digital system (p > 0.05). In general, the objective analysis was not influenced by the presence of a lead foil in any of the tested systems (p > 0.05). However, Digora Toto images showed greater gray values, lower standard deviation of gray values and lower contrast variation, regardless of the presence of the lead foil (p < 0.05). Conclusions: The addition of a lead foil to intraoral digital receptors did not influence image contrast nor caries lesions diagnosis.

This paper addresses the problem of no-reference assessing the overall image contrast. The purpose of this work is to increase the accuracy of quantifying the perceived contrast of the multi-element image. To this end, we propose a new approach to quantify the perceived contrast of a complex multi-element image. The proposed approach is based on the analysis of the dependencies of brightness increments on the image adaptation level and the size ratio of image elements. Based on the proposed approaches, new techniques for quantifying the incomplete integral contrast also are considered. Research confirms the effectiveness of the proposed approach to quantifying the perceived contrast of complex images.

Electron staining is generally performed prior to observing organic materials via transmission electron microscopy (TEM) to enhance image contrast. However, electron staining can deteriorate organic materials. Here, we demonstrate electrostatic potential imaging of organic materials via differential phase contrast (DPC) scanning transmission electron microscopy (STEM) without electron staining. Electrostatic potential imaging drastically increases the contrast between different materials. Phase-separated structures in a poly (3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) blend that are impossible to observe using conventional STEM are clearly visualized. Furthermore, annealing behavior of the phase-separated structures is directly observed. The morphological transformations in the samples are consistent with their physical parameters, including their glass transition and melting temperatures. Our results indicate that electrostatic potential imaging is highly effective for observing organic materials.

Image contrast enhancement is a common image enhancement method in various image applications. Histogram equalization (HE) is a popular conventional and improved way to enhance the image contrast. This conventional HE and its updated versions try to maintain the original image characteristics especially in original image brightness distribution during contrast enhancement. But it suffers various restrictions including false contouring, lack of original image features, etc. Optimization can be a possible solution to overcome such problems and to maintain desired image characteristics as well as enhanced image contrast. Grey wolf optimizer (GWO) is a newly high potential algorithm in the computational intelligence field to solve this type of problem. This paper presents an application of HE-based contrast enhancement using GWO. The objective function has been designed using different parameters to preserve original image characteristics. The results have been taken using the standard database of both gray and colour images. The results have also been compared against various renowned techniques by standard image quality evaluation metrics. The visual as well as parametric presentation indicates the distinguished prospective of GWO for image contrast enhancement.

Laser lights have been used by dermatologists for tattoo removal through photothermal interactions. However, most clinical studies used a visual scoring method to evaluate the tattoo removal process less objectively, leading to unnecessary treatments. This study aimed to develop a simple and quantitative imaging method to monitor the degree of tattoo removal in in vivo skin models. Sprague Dawley rat models were tattooed with four different concentrations of black inks. Laser treatment was performed weekly on the tattoos using a wavelength of 755 nm over six weeks. Images of non-treated and treated samples were captured using the same method after each treatment. The intensities of the tattoos were measured to estimate the contrast for quantitative comparison. The results demonstrated that the proposed monitoring method quantified the variations in tattoo contrast after the laser treatment. Histological analysis validated the significant removal of tattoo inks, no thermal injury to adjacent tissue, and uniform remodeling of epidermal and dermal layers after multiple treatments. This study demonstrated the potential of the quantitative monitoring technique in assessing the degree of clearance level objectively during laser treatments in clinics.

An appropriate identification of the tissue type that is in front of the excision surgical tool is critical, for either tumoral tissue removal, or even accessory healthy tissues whose destruction could cause severe collateral damage. Healthy tissue distinction is an unsolved task in real surgical praxis, due for instance to alterations or hemorrhages. Many approaches have tried to solve the problem of healthy tissue discrimination, such as spectroscopy. Diffuse Reflectance Spectroscopy (DRS), an easy to implement and reliable optical diagnostic technique, has shown great potential in tumoral tissue discrimination, as long as in healthy tissue distinction. However, the identification of nerve tissue in particular is challenging. What is more, nerve tissue distinction is critical in surgical interventions, due to the severe irreversible dysfunctions in patient mobility that collateral damage could cause. Fluorescence is an optical technique that could be of relevance for nerve identification. The need of specific fluorophores that tend to accumulate preferentially on nerve tissue is essential for this task. Image quality requires also an analysis of the optical source, filters employed, fluorophore concentration or inoculation method. Together with those aspects, additional open questions include incubation time or cytotoxicity, critical for clinical translation. In this work, fluorescence imaging for nerve identification is applied on in vivo rats. The approach uses several fluorophore concentrations, based on Oxazine, and combines topical and intravascular inoculation. Optical irradiance is considered for image contrast. The results show an appreciable nerve contrast for optimized parameters. This work has been partially supported by the project “High-pressure driven plasmonic and luminescence properties ofnaked and core/shell metal-oxide nanocomposites” (PGC2018-101464-B-I00) of the Spanish Ministry of Science, Research and Universities, cofunded by FEDER funds, and by the San Cándido Foundation.

Using the same ultrasound detector, hybrid optoacoustic-ultrasound (OPUS) imaging provides concurrent scans of tissue slices or volumes and visualizes complementary sound- and light-based contrast at similar resolutions. In addition to the benefit of hybrid contrast, spatial co-registration enables images from one modality to be employed as prior information for improving an aspect of the performance of the other modality. We consider herein a handheld OPUS system and utilize structural information from ultrasound images to guide regional Laplacian regularization-based reconstruction of optoacoustic images. Using phantoms and data from OPUS scans of human radial and carotid arteries, we show that ultrasound-driven optoacoustic inversion reduces limited-view artefacts and improves image contrast. In phantoms, prior-integrated reconstruction leads to a 50 % higher contrast-to-noise ratio (CNR) of the image than standard reconstruction, and a 17 % higher structural similarity (SSIM) index. In clinical data, prior-integrated reconstruction detects deep-seated radial arteries with higher CNR than the standard method at three different depths. In this way, the prior-integrated method offers unique insights into atherosclerotic carotid plaques in humans (with p < 0.01 between patients and healthy volunteers), potentially paving the way for new abilities in vascular imaging and more generally in optoacoustic imaging.

The generation of kinematic models of the heart using 3D echocardiography (echo) can be difficult due to poor image contrast and signal dropout, particularly at the epicardial surface. 2D echo images generally have a better contrast-to-noise ratio compared to 3D echo images, thus wall thickness (WT) estimates from 2D echo may provide a reliable means to constrain model fits to 3D echo images. WT estimates were calculated by solving a pair of differential equations guided by a vector field, which is constructed from the solution of Laplace’s equation on binary segmentations of the left ventricular myocardium. We compared 2D echo derived WT estimates against values calculated using gold-standard cardiac cine magnetic resonance imaging (MRI) to assess reliability. We found that 2D echo WT estimates were higher compared to WT values from MRI at end-diastole with a mean difference of 1.3 mm (95% CI: 0.74–1.8 mm), 1.5 mm (95% CI: 0.91–2.1 mm) and 2.1 mm (95% CI: 1.6–2.6 mm) for basal, mid-ventricular and apical segments respectively. At end-systole, the WT estimates from MRI were higher compared to those derived from 2D echo with a mean difference of 2.6 mm (95% CI: 2.0–3.1 mm), 2.1 mm (95% CI: 1.5–2.7 mm) and 1.1 mm (95% CI: 0.49–1.7 mm) for basal, mid-ventricular and apical segments, respectively. The quantitative WT comparison in this study will contribute to the ongoing efforts to better translate kinematic modelling analyses from gold-standard cardiac MRI to the more widely accessible echocardiography.

Conventional contrast enhancement methods such as histogram equalization (HE) have not obtained acceptable results on many different low-contrast images and they also cannot automatically handle various images. These problems are a result of specifying parameters manually for the sake of producing high-contrast images. We proposed an automatic image contrast enhancement on Hyper-heuristic. In this study, simple exploiters are proposed to improve the contrast of current image. To select these exploiters appropriately, reinforcement learning is proposed. This selection is based on the functional history of these exploiters. Having multi aim of preserving brightness, retaining the shape features of the original histogram, and controlling on the rate of over-enhancement are the achievements of the proposed method. These objectives are suitable for the application of consumer electronics. By this simulation results, it has been shown that in terms of visual assessment, absolute mean brightness error (AMBE) and peak signal-to-noise (PSNR) of the proposed method are superior to literature methods.

Sunlight-based lensless ghost imaging could be used to take a picture of a distant-object with 130 µm image resolution. But the image-contrast is very low. This article reports a study of this lensless ghost imaging to achieve perfect image-contrast.

Image enhancement technique is able to enhance structure of a lesion and filter out irrelevant information through an image processing method. It can make contrast of an image stronger, and therefore enhance diagnostic accuracy. Current image enhancement techniques apply global enhancement with some strategies like histogram equalization. However, local contrast information may be lost because of the use of a global enhancement. And, global enhancement may bring unnecessary information on irrelevant background tissues. For this reason, local contrast information needs to be incorporated in the global enhancement procedure. We propose a multi-view learning approach for glioblastoma image contrast enhancement. Each local contrast is accomplished by a single-view learning and therefore final enhancement is a result of multi-view learning. Experimental results demonstrate that the proposed method is able to outperform traditional global contrast enhancement techniques.

Details that are invisible to the human eye in an image with low contrast can become an indicator of inconsistencies in the relative position of objects / people in the image or their illumination, which can be considered a sign of digital tampering. The article proposes a new approach for detecting photomontage in a digital image only using methods to increase the contrast of the image.

The aspects of using optical instruments for minimally invasive interventions in abdominal surgery are considered. The results of clinical and preclinical trials of the application of the multimodal optical approaches in endoscopic instruments for the treatment and diagnosis of abdominal cancer are reviewed and discussed. A significant increase in image contrast, sensitivity, and specificity of cancer detection is noted. Novel fiber-optic system for versatile evaluation of the bile duct in patients with mechanical jaundice is described. It has been demonstrated that multimodal optical biopsy can be integrated with standard semi-automatic biopsy systems using fine-needle optical probes with immediate comparison of tumor and healthy tissue optical properties for determination of the tissue state. The applicability of this technique to the diagnosis of hepatocellular carcinoma has been demonstrated.

Objectives The aims of the present study were to assess the influence of mild to moderate hyperglycaemia and body weight on brain 2-[18F]fluoro-2-deoxy-d-glucose ([18F]FDG) PET, and to what extent a simple algorithm for maintaining count density may compensate for these effects. Methods We prospectively included 63 patients undergoing routine brain [18F]FDG PET. Scan time and injected activity were adjusted in patients with hyperglycaemia or increased body weight. Measures of perceived image quality, image noise and image contrast were obtained in both standard scans and intervention scans. Results Elevated blood glucose and increased body weight were associated with reduced count density and increased image noise that in turn were associated with lower scores of perceived image quality. The proposed simple algorithm effectively maintained the image noise level and improved perceived image quality across the full range of elevated blood glucose values and body weights, although the effect of intervention on perceived image quality was attenuated by lower image contrast in patients with moderate hyperglycaemia. In patients with increased body weight or blood glucose, the fraction of scans with poor image quality decreased from 9/29 to 2/29 (P = 0.04) and the fraction with good image quality increased from 7/29 to 20/29 (P = 0.001) when applying the proposed algorithm. Conclusions Increasing blood glucose and body weight are associated with increased image noise in standard imaging conditions. Improving count density by prolonging scan time and increasing injected activity significantly improves image quality in hyperglycaemic patients, although the image contrast remains reduced in patients with most pronounced hyperglycaemia.

Indexación: Scopus. The emblematic palace-cinemas which accompanied the rise of cinematographic exhibition in Chile during the 20th century, reflect a widespread practice codified by a series of exhibition halls that inherit the tradition of a theatrical stylistic architecture. However, this account does not take notice of another kind of halls built during the same period that entails the development of an unprecedented typology: the corner-cinema. Identified as a programmatically hybrid building, the latter incorporated specific spaces for commerce and housing in addition to the projection space, resulting in an architectural strategy that would anticipate a response to urban density. Recognizing that distinctive feature, this article exposes and classifies a set of cinemas built in Santiago and other Chilean cities that share similar characteristics in terms of their programmatic mixture and formal structures, composing a catalogue of singular works that reveals their distinctive aspects as an experience of disciplinary innovation. Located at the corner of a block, these projects not only fulfilled the requirement of modernizing the places for films as the 1920's cinematographic industry demanded, but also constituted a timely response whose logic promoted a new way to build the city. Based on this evidence, the historical perspective implied by the typological approach of this analysis provides a more general insight about the role of architecture and its ability to perform as an active component in the configuration of urban and social environment. http://www.revista180.udp.cl/index.php/revista180/article/view/746

We show that background fringe pattern subtraction is a useful technique in removing static noise from off-axis holographic reconstructions and can enhance image contrast in volumetric reconstructions by an order of magnitude.

The High-Dynamic-Range (HDR) technique, covering the HDR content acquisition, distribution and rendering, enables the detail-rich reproduction of images with large brightness differences. Besides expanding image contrast range, HDR can also contribute to the wide color gamut (WCG). On the other hand, the WCG display technique can benefit to mitigate the heat dissipation problem of HDR display. The popular red, green and blue three-primary colors can only cover a part of all the visible colors, more than three-primary colors are essential for the WCG purpose. Whereas there exist many solutions for acquiring and displaying video contents of more than three-primary colors, their distribution poses a challenge, particularly due to the valuable frequency bandwidth. Among others, this chapter will meet this challenge.

Plant segmentation is a crucial task in computer vision applications for identification/classification and quantification of plant phenotypic features. Robust segmentation of plants is challenged by a variety of factors such as unstructured background, variable illumination, biological variations, and weak plant-background contrast. Existing color indices that are empirically developed in specific applications may not adapt robustly to varying imaging conditions. This study proposes a new method for robust, automatic segmentation of plants from background in color (red-green-blue, RGB) images. This method consists of unconstrained optimization of a linear combination of RGB component images to enhance the contrast between plant and background regions, followed by automatic thresholding of the contrast-enhanced images (CEIs). The validity of this method was demonstrated using five plant image datasets acquired under different field or indoor conditions, with a total of 329 color images as well as ground-truth plant masks. The CEIs along with 10 common index images were evaluated in terms of image contrast and plant segmentation accuracy. The CEIs, based on the maximized foreground-background separability, achieved consistent, substantial improvements in image contrast over the index images, with an average segmentation accuracy of F1 = 95%, which is 4% better than the best accuracy obtained by the indices. The index images were found sensitive to imaging conditions and none of them performed robustly across the datasets. The proposed method is straightforward, easy to implement and can be potentially extended to nonlinear forms of color component combinations or other color spaces and generally useful in plant image analysis for precision agriculture and plant phenotyping.

This study describes a modified partial differential equation (PDE)-based algorithm for contrast enhancement of hazy images. The formulation is supported by similarities between haze and low light conditions. The proposed approach employs multi-scale, local-global enhancement of inverted log reflectance and illumination components. These multiple processes are combined in a suitable PDE framework for improved effectiveness. Furthermore, the de-hazing process is automated via gradient-based optimization, eliminating the manual determination of PDE stopping time. Solutions are also devised for visual halo effect, over-enhancement and colour distortion. Based on subjective and quantitative analysis, the proposed technique consistently outperforms several de-hazing algorithms from the literature.

Quantifying the therapeutic effect of acupuncture is one of the biggest challenges in the modernization of acupuncture treatment. Based on the relationship between acupuncture and human microcirculation, this paper presents a therapeutic effect detection method based on laser speckle blood perfusion imaging (LSBPI). And a blood perfusion index (PI) was defined to measure the therapeutic effect of acupuncture. Aiming at the problem of image contrast reduction caused by human shaking and other factors in acupuncture process, an automatic image matching method was proposed. The LSBPI system was tested by a simulation experiment consisting of water pump and hoses. Acupuncture experiments were performed on 10 volunteers at the point of Waiguan, and the variance of PI of the different area on the hand was compared. The results showed that the PI of the finger during the acupuncture is more than 60% higher than that in the natural state. This new technique may have practical significance in the detection of therapy effects of acupuncture.

This paper proposes a novel variant of Brightness Preserving Dynamic Histogram Equalization (BPDHE) having more brightness preserving capability with less computational time. This variant, called Variance based Brightness Preserve Dynamic Histogram Equalization (VBBPDHE) uses the interclass and intraclass variance information to segment out the histogram recursively. This variant does not need the smoothing operation of input histogram and also no need to compute local maxima or minima to segment out the histogram unlike BPDHE. Visual analysis, quality metrics and execution time clearly demonstrate the efficiency of the proposed VBBPDHE over well-known existing methods.

Purpose To evaluate the detection performance of hepatocellular carcinoma and image quality in patients with chronic liver disease with quadruple arterial MR imaging using radial volumetric imaging breath-hold examination (VIBE) with k-space weighted image contrast (KWIC). Materials and Methods Forty-four patients underwent liver MR examinations with quadruple arterial imaging using radial VIBE-KWIC sequence (full-frame and four sub-frame images). Diagnostic performance was evaluated with receiver operating characteristics (ROC) for detection of hepatocellular carcinoma. The image quality and severity of artifact were scored by using the five-point scale. Results The area under the ROC curve (Az) value of Hepatocelluar Carcinoma (HCC) detectability was the highest on third sub-frame images, followed by full-frame images. The Az values of third sub-frame and full-frame about the detection of HCC were statistically significantly different from the Az value of first sub-frame images. The full-frame and four sub-frame images showed acceptable image quality and low degree artifact with rating of higher than grade 3. Conclusion Quadruple arterial MRI using radial VIBE-KWIC is a feasible method for detecting hepatocellular carcinoma in patients with chronic liver disease without deterioration of image quality. The third sub-frame and full-frame image are superior to other sub-frame images in detecting hepatocellular carcinoma.

Similar subtraction imaging is useful for the detection of lung nodules; however, some artifacts on similar subtraction images reduce their utility. The authors attempted to improve the image quality of similar subtraction images by reducing artifacts caused by differences in image contrast and sharpness between two images used for similar subtraction imaging. Image contrast was adjusted using the histogram specification technique. The differences in image sharpness were compensated for using a pixel matching technique. The improvement in image quality was evaluated objectively based on the degree of artifacts and the contrast-to-noise ratio (CNR) of the lung nodules. The artifacts in similar subtraction images were reduced in 94% (17/18) of cases, and CNR was improved in 83% (15/18) of cases. The results indicate that the combination of histogram specification and pixel matching techniques is potentially useful in improving image quality in similar subtraction imaging.

The article discusses various methods of image quality assessment. A comparative analysis of sharpness functions as a measure of image quality, in the absence of a standard for comparison, was conducted.

The manner in which magnetized plasma jets evolve remains key to better understanding the behavior of hydromagnetic systems and providing new insights into how they can be dynamically controlled. In this work, we present the underlying theory, apparatus, and optical features of a schlieren diagnostic capable of cinematically visualizing dense plasma jets. We identify the range of plasma density over which the diagnostic is sensitive and describe ways to further improve image contrast. This diagnostic features the unique ability to simultaneously resolve both the characteristic Alfvenic timescales and spatial flow features with continuous acquisition over the lifetime of a jet. We use this diagnostic to visualize the formation and evolution of hydromagnetic jets produced from a plasma gun device. Dynamic coherent flow features are identified and tracked over time throughout the evolutionary progression of plasma jets. Finally, the process by which these coherent features translate into perturbations of magnetized bow shocks is visualized.

In optoacoustic tomography, image reconstruction is often performed with incomplete or noisy data, leading to reconstruction errors. Significant improvement in reconstruction accuracy may be achieved in such cases by using nonlinear regularization schemes, such as total-variation minimization and L1-based sparsity-preserving schemes. In this paper, we introduce a new framework for optoacoustic image reconstruction based on adaptive anisotropic total-variation regularization, which is more capable of preserving complex boundaries than conventional total-variation regularization. The new scheme is demonstrated in numerical simulations on blood-vessel images as well as on experimental data and is shown to be more capable than the total-variation-L1 scheme in enhancing image contrast. Keywords: Optoacoustic imaging, Total variation, Inversion algorithms, Model-based reconstruction

A novel differential interference contrast microscope (DICM) is proposed in this research. It is constituted by inserting a Savart shear prism between the objective and sample of a polarising microscope having a rotatable analyser as the phase-shifter, and it is with the ability to enhance image contrast using the principle of shearing interferometry. This letter is to introduce the configuration, interpret the interference patterns and present the experimental setup of the DICM. In addition, this letter is to display the experimental results from the uses of the setup; the results demonstrate the validity and ability of the DICM.

Deep underwater images suffer from several problems, such as low contrast and visibility, which reduce the extraction rate of valuable information from the image. In this paper, we proposed an approach which integrates the three main steps of homomorphic filtering, recursive-overlapped CLAHS and dual-image wavelet fusion and thus increases the visibility of deep underwater images and the extraction rate of important data. Additionally, this approach implements homomorphic filtering to provide homogeneity in the illumination of the entire image which will be used for subsequent processes. Recursive-overlapped CLAHS refers to the recursive process of overlapped tiles of divided image channel, where half of a tile is processed twice with an adjacent tile. Half of the tile is overlapped with its next adjacent tile. Dual-image wavelet fusion merging two images obtained from the integration of upper- and lower-stretched histograms are applied with discrete wavelet transformation before the main process of wavelet fusion is implemented. Qualitative and quantitative results reveal that the proposed method outperforms the current state-of-the-art methods. The highest value of average quantitative evaluations in terms of entropy, average gradient, measure of enhancement (EME) and EME by entropy are 7.835, 12.802, 8.343 and 27.616, respectively, in the proposed method.