Magnification Method Research Articles

A method of holographic magnification based on Fresnel diffraction

AbstractIn this paper, we propose a method of holographic magnification based on Fresnel diffraction. Similarity principle of Fourier transform is used in convolution algorithm in order to adjust the size of the reconstructed image. With the splicing technology based on a spatial light modulator, the reconstructed images can be magnified. By combining the similarity principle of Fourier transform with the splicing technology, the reconstructed images can be further magnified to eight times, which is verified by the experiments.

Development of the local magnification method for quantitative evaluation of endoscope geometric distortion.

With improved diagnostic capabilities and complex optical designs, endoscopic technologies are advancing. As one of the several important optical performance characteristics, geometric distortion can negatively affect size estimation and feature identification related diagnosis. Therefore, a quantitative and simple distortion evaluation method is imperative for both the endoscopic industry and the medical device regulatory agent. However, no such method is available yet. While the image correction techniques are rather mature, they heavily depend on computational power to process multidimensional image data based on complex mathematical model, i.e., difficult to understand. Some commonly used distortion evaluation methods, such as the picture height distortion (DPH) or radial distortion (DRAD), are either too simple to accurately describe the distortion or subject to the error of deriving a reference image. We developed the basic local magnification (ML) method to evaluate endoscope distortion. Based on the method, we also developed ways to calculate DPH and DRAD. The method overcomes the aforementioned limitations, has clear physical meaning in the whole field of view, and can facilitate lesion size estimation during diagnosis. Most importantly, the method can facilitate endoscopic technology to market and potentially be adopted in an international endoscope standard.

Physiological Signal Extraction based Liveness Detection Method for Face Recognition System

Recently, biometric techniques are used widely in field of security system. Especially, face recognition is one of popular biometrics due to its intuitiveness and convenience. However, human face is always exposed and likely to be a target of spoofing attack. Thus, in face recognition security system, fake face detection is important issue as much as face recognition. In general, human skin color is vary under the influence of blood flow but it is impossible to perceive such variation with naked eye. Fortunately, a proposed skin color magnification method makes it possible to capture these variations. From that, we extract the Received (January 11, 2016), Review Result (January 25, 2016) Accepted (February 1, 2016), Published (March 31, 2016) 110-743 Department of Computer Science, Sangmyung Univ., 7 Hongji-dong, Jongno-gu, Seoul, Korea email: tjrjsgk@naver.com (Corresponding Author) 110-743 Department Computer Science, Sangmyung Univ., 7 Hongji-dong, Jongno-gu, Seoul, Korea email: eclee@smu.ac.kr * 본 연구는 미래창조과학부 및 정보통신기술진흥센터의 대학ICT연구센터육성 지원사업의 연구결과로 수행되 었음 (IITP-2015-R0992-15-1014) Physiological signal extraction based liveness detection method for face recognition system Copyright c 2016 HSST 52 physiological signal from face skin then distinguish the captured face by camera whether the face image is live or not. Proposed method has no need to training process before use and does not require user to any behavior or facial expression. Experiment result showed that the real and fake(facial photo) has distinctive results in terms of inflection point of the extracted physiological signal.

High-resolution images based on directional fusion of gradient

This paper proposes a novel method for image magnification by exploiting the property that the intensity of an image varies along the direction of the gradient very quickly. It aims to maintain sharp edges and clear details. The proposed method first calculates the gradient of the low-resolution image by fitting a surface with quadratic polynomial precision. Then, bicubic interpolation is used to obtain initial gradients of the high-resolution (HR) image. The initial gradients are readjusted to find the constrained gradients of the HR image, according to spatial correlations between gradients within a local window. To generate an HR image with high precision, a linear surface weighted by the projection length in the gradient direction is constructed. Each pixel in the HR image is determined by the linear surface. Experimental results demonstrate that our method visually improves the quality of the magnified image. It particularly avoids making jagged edges and bluring during magnification.

A New Wavelet Based Spatio-temporal Method for Magnification of Subtle Motions in Video

Video magnification is a computational procedure to reveal subtle variations during video frames that are invisible to the naked eye. A new spatio-temporal method which makes use of connectivity based mapping of the wavelet sub-bands is introduced here for exaggerating of small motions during video frames. In this method, firstly the wavelet transformed frames are mapped to connectivity space and then decomposed into different spatial frequency bands by applying Laplacian Pyramid to determine the pixels having more chance to be a part of a movement. Finally each candidate is partially magnified based on its time history. The performance of the proposed method is evaluated on real videos which contain several subtle motions. Parameters for performance evaluation are presented and obtained results are compared with one of state-of-the-art video magnification methods. Increased true positive rate in parallel with simultaneous decrease in false positive rate confirm the effectiveness of the proposed method in amplifying subtle motions.

Accuracy of Various Diagnostic Aids in Detection of MB2 Canal in Maxillary First Molar: In vivo Study

ABSTRACT Aim To evaluate and compare the accuracy of radiographic, visual, dye and magnification method in detection of second mesiobuccal (MB2) canal in maxillary first molar. Materials and methods One hundred males and females patients in age group of 20 to 45 years with maxillary first molar teeth indicated for root canal treatment were selected for the study. The presence of MB2 canal in maxillary first molar was observed by four independent observers using radiographic, visual, dye, magnification diagnostic aids. Results The study showed that there was a large difference in detecting MB2 canal in maxillary first molar when radiographic was compared with visual method and magnification method (i.e., p < 0.01). Whereas there was a nonsignificant difference when radiographic and dye method were compared (i.e., p > 0.05). Conclusion It was concluded that the incidence of MB2 canal in mesiobuccal roots of permanent maxillary first molars was detected most using magnification method, i.e., 87%. Accuracy of radiographic method was found to be least, i.e., 19%. How to cite this article Mulay S, Kadam G, Jain H. Accuracy of Various Diagnostic Aids in Detection of MB2 Canal in Maxillary First Molar: In vivo Study. World J Dent 2016;7(2):78-82.

Root Canal Stripping: Malpractice or Common Procedural Accident-An Ethical Dilemma in Endodontics.

Root canal stripping is defined as an oblong, vertical perforation that appears especially in the middle section of curved root canals during endodontic treatments with nickel-titanium (Ni-Ti) instruments. Its occurrence may drastically affect the outcome of the treatment, transforming a common otherwise efficient endodontic procedure into a complication such as tooth extraction. In order to discuss the ethical and legal consequences, two cases of dental strip perforations are herewith presented. Due to the existence of risk factors for dental strip perforation, experience of the clinician and the use of magnification and modern imagistic methods (CBCT) may avoid or reduce the frequency of this type of accidents. Under correct working circumstances, dental stripping should not be regarded as a malpractice but as a procedural accident. However, the patient must always be informed, before and during the endodontic procedure, about the event and the possible complications that may occur.

Identification of structural domains considering the size effect of rock mass discontinuities: A case study of an underground excavation in Baihetan Dam, China

This study used a case study of an underground excavation in Baihetan Dam, China to identify structural domains, which are highly affected by size effects. The magnification and reduction methods involving nonparametric hypothesis tests of the KS, T-, and F-tests were proposed for the identification of structural domains. This process considers the fracture properties of orientation, trace length, position, and density. An ideal fractured rock mass model, whose structural domain identification reliability can easily be assessed, was generated and the size effect was proved to be significant. A sampling window with 159 stochastic fractures along an underground excavation was then presented. Calculations showed that different calculation sizes produce apparently different identification results. Given the objective of the analysis and further calculations, reliable results for the magnification and reduction methods were obtained.

A Method of Image Magnification Based on Radial Basis Function

A Method of Image Magnification Based on Radial Basis Function

Simplified design method for slender hybrid columns

This paper deals with numerical investigations on second-order effects in slender RC columns reinforced by several steel sections, namely hybrid columns, subjected to combined axial load and uniaxial bending moment. A FE model is developed in which geometrical and material nonlinearities as well as the partial interaction effect between the steel profiles and the surrounding concrete are taken into account. This model is then used to perform an extensive numerical parametric study on the ultimate load of hybrid columns considering 1140 different data sets. The comparison between the results obtained with FE analysis and Eurocode simplified methods (moment magnification approach) shows that EC2 and EC4 methods give wide discrepancies where half of case-studies are unsafe. The aim of the paper is to extend the use of the Eurocode moment magnification method to slender hybrid column design. In this method, the second-order bending moment is calculated by multiplying the first-order one by a magnification factor k that depends on the flexural stiffness EI and the equivalent moment distribution. New expressions for the correction factors involved in the determination of the effective flexural stiffness EI are proposed and calibrated by the results of the extended parametric study with 2960 data sets. The comparison of the predictions given by the new expressions against the FE analysis shows that the proposed new expressions of correction factors for moment magnification method provides largely safe designs for slender hybrid columns.

Comparison of the Diagnostic Usefulness of Conventional Magnification and Near-focus Methods with Narrow-band Imaging for Gastric Epithelial Tumors

Background/Aims: Dual-focus two-stage optical lens technology has been introduced recently. In near-focus mode (NFM), endoscopists can easily examine the mucosal tissue and capillary networks. This study compared the magnified images obtained using NFM and the conventional magnification method (CMM) under narrow-band imaging in patients with gastric epithelial tumors. Materials and Methods: An experienced endoscopist performed endoscopy using NFM and CMM in patients with gastric epithelial tumors. We studied 40 images from 40 endoscopy sessions in 20 selected patients. Ten endoscopists rated the image quality independently on a 5-point Likert scale (from poor=1 to excellent=5) in terms of microsurface structure, microvascular structure, and the demarcation line. Results: The gastric epithelial tumors comprised 10 cases of early gastric cancer, 2 of high-grade dysplasia, and 8 of low-grade dysplasia. The median number of magnified images for each method was 11. The mean observation time (±SD) for magnification was 99.9±64.1 s in NFM and 91.5±64.6 s in CMM (P=0.54). The image quality score for the microsurface structure was higher with NFM than CMM (4.09±0.39 vs. 3.73±0.40, P=0.015), while that for microvascular structure was lower with NFM than in CMM (3.53±0.45 vs. 4.29±0.45, P=0.001). Conclusions: Magnification using NFM provides higher-quality images of the microsurface structure, although its optical zoom is limited compared with CMM. Since NFM can obtain magnified images easily by pushing a button on the scope, it is useful for evaluating gastric epithelial tumors. (Korean J Helicobacter Up Gastrointest Res 2015;15:39-43)

Mediated-reality magnification for macular degeneration rehabilitation

Age-related macular degeneration (AMD) is a gradually progressive eye condition, which is one of the leading causes of blindness and low vision in the Western world. Prevailing optical visual aids compensate part of the lost visual function, but omitting helpful complementary information. This paper proposes an efficient magnification technique, which can be implemented on a head-mounted display, for improving vision of patients with AMD, by preserving global information of the scene. Performance of the magnification approach is evaluated by simulating central vision loss in normally sighted subjects. Visual perception was measured as a function of text reading speed and map route following speed. Statistical analysis of experimental results suggests that our magnification method improves reading speed 1.2 times and spatial orientation to find routes on a map 1.5 times compared to a conventional magnification approach, being capable to enhance peripheral vision of AMD subjects along with their life quality.

Effects of Auditory Cues for Linear and Differential Magnification Methods on Visual Inspection Performance

AbstractThe unfavorable consequence of biased attention to peripheral objects was reported with the use of a newly proposed differential magnification method by the authors. Given the favorable influence of auditory cueing on attention orientation, this study investigated the effectiveness of auditory cues in directing participants’ attention from the peripheral to foveal areas of the differential magnifying lens for improving inspection performance. Thirty‐nine Chinese undergraduates performed a simulated inspection task using a particular magnification method (between‐participant factor). Three within‐participant factors of auditory cue interval, target difficulty, and magnification power were tested. Objective performance measures of speed and accuracy and subjective evaluation using NASA task load index were collected and analyzed. The results showed that positive effects of auditory cues were found for the differential magnification methods but not for the traditional linear magnification method. Significant effects of target difficulty and magnification power were also found. It was concluded that the aid of auditory cues, which did not share the same attentional resource with the visual inspection task, proved to be an appropriate reminder for the differential magnification methods to improve participants’ visual inspection performance. Attention should also be paid to selecting an appropriate auditory cue interval for search tasks of different target difficulties. The findings of this study have implications for the design of video magnifiers in the context of multimodal human–machine interfaces.

A New Magnification Method for RGB Color Images Based on Subpixels Decomposition

In this letter, we introduce a new image magnification method based on subpixel estimation. Different from general methods, we consider each pixel in an RGB color image as a linear combination of distinct object classes, and decompose it to an appropriate set of subpixels. This is done through a local search in a lookup table to get best matches, considering the pixel intensity level and its neighboring structure. The lookup table is obtained from input image which contains same target classes. This eliminates the need of any other training sets. The presented method is simple, capable of online implementation and preserves edges better. The results also show better visual effects and objective measures of quality and sharpness compared to interpolation methods.

Application of a three-dimensional microsurgical video system for a rat femoral vessel anastomosis

Background The operating microscopes have been applied to modern surgery for nearly a century. However, generations of microsurgeons have to flex their necks and fix their eyes on the eyepieces of a microscope continually that leads to physical and mental fatigue during a long operation. Stereoscopic three-dimensional (3D) media provides more ergonomic working environment, subsequently, resulting better performance in tasks and more accurate judgment. In this study, an alternative method of magnification was analyzed using a three-dimensional microsurgical video system and compared with the traditional method under microscopy to evaluate the availability and feasibility of a 3D microsurgical video system for microvascular anastomosis. Methods Forty Sprague-Dawley rats were randomly divided into four groups with each of 10. In 20 rats, 10 femoral artery anastomoses with a conventional microscope (arterial microscope group) were compared with that of 10 femoral artery anastomoses with a 3D microsurgical video system (arterial 3D group). For the other 20 rats, 10 femoral vein anastomoses using a conventional microscope (venous microscope group) were compared with that of 10 femoral vein anastomoses using a 3D microsurgical video system (venous 3D group). The arterial and venous microscope groups were considered to be the control groups. The arterial and venous 3D groups were the experimental groups. The examined criteria were as follows: anastomotic time, patency right after the procedure and 10 days later, number of sutures, vessel caliber, and pathological features. Results There were no differences between the operating equipment with respect to vessel caliber, anastomotic time, patency rate, number of sutures, and pathological changes in either the small arteries or veins. The average arterial anastomotic time of the arterial microscope group and arterial 3D group was 34.21 and 33.87 minutes, respectively (P >0.05). The average venous anastomotic time of the venous microscope group and venous 3D group was 29.95 and 31.50 minutes, respectively (P >0.05). Conclusions A small vessel anastomosis can be performed successfully with the help of a 3D display system. Although the vascular anastomotic time did not demonstrate a significant difference between the groups, the 3D microsurgical video system offers another option to improve the working environment for surgeons. Further development of our 3D monitoring system should focus on a higher resolution and better flexibility.

Image Interpolation Based on Wavelet Transform

Image interpolation is widely studied and used in digital image processing. In this paper, a method of image magnification according to the properties of fractal interpolation and wavelet transformation are presented. We focus the development of edge forming methods to be applied as a post process of standard image zooming methods for grayscale images, with the hope of retaining edges. Experiments make sure it valid.

Assessment of nailfold capillaroscopy in systemic sclerosis by different optical magnification methods

Systemic sclerosis (SSc) is characterized by target-organ fibrosis and microvascular dysfunction, which can be assessed using nailfold capillaroscopy. Dermoscopy is a useful and easily performed method for diagnosing skin lesions. To compare conventional capillaroscopy, using the gold-standard method (conventional stereomicroscope nailfold capillaroscopy; SNFC), with polarized light noncontact dermoscopy (PNCD) and nonpolarized light contact dermoscopy (NPCD), and to evaluate their accuracy in diagnosing characteristic SSc-related alterations. The study enrolled 45 patients with SSc. Capillaroscopy images and photographs were taken with three devices, SNFC, NPCD and PNCD, and these images were randomly analysed by a blinded observer. The scleroderma pattern was found in 83% of patients. PNCD and NPCD were highly sensitive in identifying the presence of focal capillary loss (96.4% and 100%, respectively), haemorrhage (96.2% and 92%, respectively), and scleroderma (91.9%, 94.6%), and showed high specificity for haemorrhage and enlarged loops. The intra-observer kappa values for detection of the scleroderma pattern by SNFC images, NPCD and PNCD were moderate to good: (κ = 0.71 (95% CI 0.44-0.95), κ = 0.60 (95% CI 0.35-0.83) and κ = 0.60 (95% CI 0.32-0.86), respectively. Evaluation of haemorrhage presence gave high kappa values for all methods: κ = 0.77 (95% CI 0.57-0.95), κ = 0.90 (95% CI 0.76-1.00) and κ = 0.95 (95% CI 0.85-1.00), respectively. Both polarized and nonpolarized dermoscopy are reliable methods for valuation of nailfold capillaroscopy in patients with SSc. They are easy to perform, with good rates of accuracy and results that are comparable with traditional capillaroscopy.

Assessment of the Confidence of the Adhesive Remnant Index Score With Different Methods

ABSTRACT Objective: The purpose of this in vitro study was to investigate the reliability of the adhesive remnant index (ARI) score system with different assessment methods and to test the compatibility of the estimators. Materials and Methods: Sixty-eight human premolars were used in this study. The premolar brackets (SmartClip, 3M Unitek, Monrovia, CA, USA) were bonded with a light cure adhesive (Transbond XT, 3M Unitek). Brackets were debonded using a Lloyd LRX testing machine (Lloyd Instruments Plc., Fareham, Hampshire, UK). Special image analysis software with ×20 magnification and naked-eye assessment methods were used to evaluate the adhesive remnant. Four different investigators scored the same samples according to a 4-point scale. The Kendall rank correlation coefficient was used to test the reliability of the estimator's scores. The Friedman test, followed by the Wilcoxon signed-ranks test, was used to investigate significant differences in the ARI scores between the different assessment methods...

Investigation into the outcomes following fixation of fractured neck of femurs with cannulated hip screws

Investigation into the outcomes following fixation of fractured neck of femurs with cannulated hip screws

Four‐Dimensional Geometry Lens: A Novel Volumetric Magnification Approach

AbstractWe present a novel methodology that utilizes four‐dimensional (4D) space deformation to simulate a magnification lens on versatile volume datasets and textured solid models. Compared with other magnification methods (e.g. geometric optics, mesh editing), 4D differential geometry theory and its practices are much more flexible and powerful for preserving shape features (i.e. minimizing angle distortion), and easier to adapt to versatile solid models. The primary advantage of 4D space lies at the following fact: we can now easily magnify the volume of regions of interest (ROIs) from the additional dimension, while keeping the rest region unchanged. To achieve this primary goal, we first embed a 3D volumetric input into 4D space and magnify ROIs in the fourth dimension. Then we flatten the 4D shape back into 3D space to accommodate other typical applications in the real 3D world. In order to enforce distortion minimization, in both steps we devise the high‐dimensional geometry techniques based on rigorous 4D geometry theory for 3D/4D mapping back and forth to amend the distortion. Our system can preserve not only focus region, but also context region and global shape. We demonstrate the effectiveness, robustness and efficacy of our framework with a variety of models ranging from tetrahedral meshes to volume datasets.