Dual Images Research Articles

Corneal topography and angle parameters after laser iridotomy combined with iridoplasty assessed by dual Scheimpflug analyzer.

To investigate the changes in corneal topography including parameters such as corneal curvature and corneal aberrations, along with anterior chamber angle (ACA) after laser iridotomy (LI) combined with peripheral iridoplasty (PI) using dual Scheimpflug analyzer. In this prospective observational study, dual Scheimpflug analyzer images were acquired before and 1week after LI plus PI. Corneal curvature of both axial and instantaneous maps from anterior and posterior surface, respectively, and total corneal power (TCP) were acquired. These corneal parameters from three zones (central, middle, and peripheral) and total corneal wavefront aberration, trefoil, and coma were obtained. The ACA from four quadrants, anterior chamber depth (ACD), anterior chamber volume (ACV), and intraocular pressure (IOP) were also inspected. ACD increased significantly from 2.15 ± 0.25 to 2.18 ± 0.24mm (P = 0.002). ACV and ACA from all four quadrants increased significantly after the laser treatment (all P < 0.05). IOP decreased significantly from 16.9 ± 3.1 to 14.7 ± 2.9mmHg following LI plus PI (P = 0.000). No significant changes were detected in corneal axial and instantaneous curvature from three zones on the anterior and posterior corneal surface after LI plus PI (all P > 0.05). The TCP, total corneal wavefront aberration, trefoil, and coma also revealed no significant changes after the laser procedure (all P > 0.05). Treatment with LI combined with PI did not affect the corneal topographic parameters from both anterior and posterior surfaces. However, LI plus PI improved ACA parameters significantly and effectively.

Incorporating iris, fingerprint and face biometric for fraud prevention in e‐passports using fuzzy vault

A unified frame work which provides a higher security level to e-passports is proposed. This framework integrates face, iris and fingerprint images. It involves three layers of security: the first layer maps a biometric image to another biometric image which is called biostego image. Three mapping schemes are proposed: the first scheme maps single biometric image to single biostego image, the second scheme maps dual biometric images to single biostego image, the third scheme divides the biometric image into sections and maps each section to different biostego image. A mapping function maps the intensity value of each pixel in the biometric image to pixels with same intensity in the biostego image. A representative pixel is randomly selected from the set of pixels, its coordinates are recorded in the location map of the biometric image. In the second layer, the location map is encoded using fingerprint fuzzy vault. In the third layer, the encoded location map is hidden in the biostego image using steganography technique. The biostego image which contains the encoded location map is stored in the e-passport’s memory. Keeping the mapping scheme secret and by using the fingerprints fuzzy vault to encrypt location map the proposed approach provides higher level of protection against fraud.

Supervised feature learning by adversarial autoencoder approach for object classification in dual X-ray image of luggage

X-ray inspection by control officers is not always consistent when inspecting baggage since this task are monotonous, tedious and tiring for human inspectors. Thus, a semi-automatic inspection makes sense as a solution in this case. In this perspective, the study presents a novel feature learning model for object classification in luggage dual X-ray images in order to detect explosives objects and firearms. We propose to use supervised feature learning by autoencoders approach. Object detection is performed by a modified YOLOv3 to detect all the presented objects without classification. The features learning is carried out by labeled adversarial autoencoders. The classification is performed by a support vector machine to classify a new object as explosive, firearms or non-threatening objects. To show the superiority of our proposed system, a comparative analysis was carried out to several methods of deep learning. The results indicate that the proposed system leads to efficient objects classification in complex environments, achieving an accuracy of 98.00% and 96.50% in detection of firearms and explosive objects respectively.

Exponential subtraction in 3D ultrashort echo time imaging to visualize short T2 tissues in tibia.

Short T2 tissues can be directly visualized by dual-echo ultrashort echo time imaging with weighted subtraction. As a type of post-processing method, exponential subtraction of ultrashort echo time images with an optimal exponential factor is expected to provide improved positive short T2 contrast. To test the feasibility and effectiveness of exponential subtraction in three-dimensional ultrashort echo time imaging and to determine the optimal exponential factor. A dual-echo three-dimensional ultrashort echo time sequence was implemented on a 3-T MRI system. Exponential subtraction was performed on dual three-dimensional ultrashort echo time images of the tibia of seven healthy volunteers with exponential factors in the range of 1.00-3.00 in increments of 0.01. The regions of interest, including cortical bone, marrow, and muscle, were depicted on subtracted images of different exponential factors. Contrast-to-noise ratio values were calculated from these regions of interest and then used to assess the optimal exponential factor. To determine intra-observer agreement regarding region of interest selection, paired intra-observer measurements of regions of interest in all direct subtraction images were conducted with a one-week interval and the paired measurements were assessed using Bland-Altman analysis and paired-samples t-test. Cortical bone can be better visualized by using exponential subtraction in three-dimensional ultrashort echo time imaging; the suggested optimal exponential factor is 1.99-2.03 in the tibia. Paired measurements showed excellent intra-observer agreement. It is feasible to visualize cortical bone of the tibia using exponential subtraction in three-dimensional ultrashort echo time imaging. Compared with weighted subtraction images, exponential subtraction images with an optimal exponential factor provide enhanced visualization of short T2 tissues.

A square lattice oriented reversible information hiding scheme with reversibility and adaptivity for dual images

This paper proposes an adaptive dual-image-based reversible information hiding scheme. First, for a pixel pair in the original image, an associated square lattice is selected to determine the maximum distortion that will be induced by hiding information. Then, an embedding rule, which combines the selected square lattice with integer rounding, is constructed. In addition, a novel histogram shifting mechanism to solve the problems of overflow and underflow is designed to decrease the distortions that are caused by the shifting of a large number of pixels. In our approach, both the original image and the secret messages can be recovered losslessly. Our experimental results show that the proposed scheme achieved performance that was superior to the state-of-the-art schemes, resulting in embedding rates up to 1.40 bpp and average PSNRs of approximately 47.60 dB. The proposed scheme also can be used in real-time systems due to the simplicity of its computations.

Using neighborhood gray tone difference matrix texture features on dual time point PET/CT images to differentiate malignant from benign FDG-avid solitary pulmonary nodules

ObjectiveLung cancer usually presents as a solitary pulmonary nodule (SPN) on diagnostic imaging during the early stages of the disease. Since the early diagnosis of lung cancer is very important for treatment, the accurate diagnosis of SPNs has much importance. The aim of this study was to evaluate the discriminant power of dual time point imaging (DTPI) PET/CT in the differentiation of malignant and benign FDG-avid solitary pulmonary nodules by using neighborhood gray-tone difference matrix (NGTDM) texture features.MethodsRetrospective analysis was carried out on 116 patients with SPNs (35 benign and 81 malignant) who had DTPI 18F-FDG PET/CT between January 2005 and May 2015. Both PET and CT images were acquired at 1 h and 3 h after injection. The SUVmax and NGTDM texture features (coarseness, contrast, and busyness) of each nodule were calculated on dual time point images. Patients were randomly divided into training and validation datasets. Receiver operating characteristic (ROC) curve analysis was performed on all texture features in the training dataset to calculate the optimal threshold for differentiating malignant SPNs from benign SPNs. For all the lesions in the testing dataset, two visual interpretation scores were determined by two nuclear medicine physicians based on the PET/CT images with and without reference to the texture features.ResultsIn the training dataset, the AUCs of delayed busyness, delayed coarseness, early busyness, and early SUVmax were 0.87, 0.85, 0.75 and 0.75, respectively. In the validation dataset, the AUCs of visual interpretations with and without texture features were 0.89 and 0.80, respectively.ConclusionCompared to SUVmax or visual interpretation, NGTDM texture features derived from DTPI PET/CT images can be used as good predictors of SPN malignancy. Improvement in discriminating benign from malignant nodules using SUVmax and visual interpretation can be achieved by adding busyness extracted from delayed PET/CT images.

Visualization of stent apposition after stent-assisted coiling of intracranial aneurysms using high resolution 3D fusion images acquired by C-arm CT

PurposeWe used an imaging technique based on 3-dimensional (3D) C-arm CT to assess the apposition of three types of stents after coiling of intracranial aneurysms.MethodsAll patients with intracranial aneurysms were...

High fidelity based reversible data hiding using modified LSB matching and pixel difference

Owing to the inefficiency to hide large volume of secret data for the reversible data hiding (RDH) image steganography approaches, we propose two improved RDH based approaches, such as (1) improved dual image based least significant bit (LSB) matching with reversibility, and (2) n-rightmost bit replacement (n-RBR) and modified pixel value differencing (MPVD). The first approach extends the ability of LSB matching with reversibility using dual images. Whereas the second approach utilizes four identical cover images for secret data embedding using two phases, such as (1) n-rightmost bit replacement (n-RBR) and (2) modified pixel value differencing (MPVD). In the n-RBR phase, n bits of secret data are embedded in the pair of two neighboring pixels of the first two identical images, where 1 ≤ n ≤ 4. Correspondingly, the MPVD phase uses the third and fourth identical images for hiding the secret data. Experimental results with respect to peak signal-to-noise ratio (PSNR), embedding capacity (EC), structural similarity index (SSIM), and the comparative analysis with recently proposed state-of-art approaches exhibit the superiority of the proposed approach. Besides reversibility, the proposed approach ensures high fidelity to salt and pepper (S&P) noise, RS analysis, and pixel difference histogram (PDH) analysis.

Quantitative phase imaging via a cGAN network with dual intensity images captured under centrosymmetric illumination

We report an end-to-end approach for quantitative phase imaging based on two intensity measurements. In our approach, we sequentially illuminate the thin complex object using two centrosymmetric LEDs whose incident angles are close to the maximum acceptance angle of the objective lens. We then feed the two acquired images to a conditional generative adversarial network (cGAN) to generate the phase image of a complex object. We show that the cGAN is able to directly learn the mapping relationship from the intensity pair to the targeted phase distribution. The effectiveness of the proposed approach is validated using both simulation and experimental data.

Real-time Indocyanine Green Videolymphography Navigation for Lymphaticovenular Anastomosis

Summary:Indocyanine green (ICG) lymphography is a useful imaging modality for evaluation of lymphedema and detection of lymphatic vessels. It also allows us to ensure patency of the anastomosed vessels intraoperatively. However, strong light from the operating microscope usually disturbs ICG fluorescence imaging. Only some built-in ICG camera systems with specific operating microscopes make real-time ICG lymphography possible in lymphaticovenular anastomosis (LVA). We applied a new high-resolution ICG videolymphography system, which is separated from the operating microscope. Because the system can divide near-infrared fluorescence light of ICG from visible light of the operating microscope, real-time ICG videolymphography-navigated LVA under operating microscope illumination is possible regardless types of operating microscopes. The study involved 10 patients with upper extremity lymphedema characterized by International Society of Lymphology stage 2 and treated by 3 lymphaticovenular anastomoses at the forearm (30 lymphaticovenular anastomoses incorporating 30 lymphatic vessels) under real-time ICG videolymphography. The rate of intraoperative detection of lymphatic vessels using real-time ICG videolymphography was 86.7% (0.25–0.85 mm in diameter), and that of lymph flow through the lymphaticovenular anastomoses was 76.7%. None of lymphatic vessels and no flow were detected under the microscope light by means of another non-built-in ICG lymphography camera. Real-time ICG videolymphography in LVA is beneficial, because the surgeon could find lymphatic vessels easily by checking dual images of original view and ICG fluorescent view and ensure accuracy of the LVA in a suture by a suture without any pauses of the surgical procedures.

A new data encoding based on maximum to minimum histogram in reversible data hiding

ABSTRACTThe dual stego images based on data hiding has become popular in recent days. Since the embedding rate in dual stego images is very high. This paper proposes a new data encoding method based on maximum to the minimum histogram in reversible data hiding. This method estimates the encoded intensity from the message intensity and embeds the encoded intensity in the cover image. The stego image quality decreases the intensity of the hidden data which is high. The intensity of the data must be kept low to maintain a high-quality stego image. It is achieved using data encoding. Therefore, the proposed method uses new data encoding which converts the higher histogram data to lower intensity and the lower histogram data to higher intensity during the data embedding process. In the extraction process, the encoded intensities are decoded to message intensities to obtain the original data. The proposed data hiding approach has improved in terms of image quality (PSNR), structure similarity index measurements and embedding rate.

교차배열 변환기를 이용한 복합 위상배열 초음파 영상화 기법 : 영상화 알고리즘 및 이중 선형 영상

교차배열 변환기를 이용한 복합 위상배열 초음파 영상화 기법 : 영상화 알고리즘 및 이중 선형 영상

Dual fluoroscopic evaluation of human tibiofemoral joint kinematics during a prolonged standing: A pilot study

A complete knowledge of tibiofemoral joint kinematics is essential for understanding the function of the healthy and pathological joint. The objective of the present study was to establish a dual fluoroscopic measurement protocol and a data processing approach for the creep response of the knee joint in order to further evaluate the mechanical properties of articular cartilage and meniscus in vivo. A computational approach was developed for the determination of 3D translations and rotations of the joints of young participants with no history of injury using dual fluoroscopic images of loaded joints and joint geometry reconstructed from magnetic resonance imaging of the unloaded joints. High-resolution X-ray images were obtained for the distal femur and proximal tibia during 10-min standing when approximately ¾ body weight was slowly applied to the right leg and then kept constant for the rest duration of the test. Anatomic coordinate systems were established for the 3D models of distal femur and proximal tibia. Translations and rotations of the joint as functions of time were then evaluated using the X-ray images and these coordinate systems with the JointTrack software. The displacements in the proximal-distal direction obtained from two participants were consistent, showing a substantial increase in the initial phase when joint loading increased from nil to ¾ body weight and a continued small increase over time while the joint loading remained constant. The maximum anterior-posterior translations during 10-min standing were approximately 4 mm for both participants, although one showed better stability than the other. In conclusion, a creep loading protocol of the knee joint can be reasonably established for in vivo conditions and evaluated with the image-based computational approach.

Q-plate based dual image asymmetric polarization encryption

With the rapid development of computer network technology, information security has drawn considerable attention in recent years. Owing to the characteristics of multi-dimensional operation and parallel processing capability, optical image encryption techniques are arousing great interest in many exciting fields. Since the pioneering work on optical image encryption using double random phase encoding technique, a large number of algorithms and architectures have been proposed and realized. However, with the further analysis of the securities of these schemes, most of them have been verified to be vulnerable to different types of attack algorithms. Recently, optical encryption schemes based on the polarization properties of light wave have been extensively studied, for an additional flexibility in the encryption key design is provided, which can achieve high robustness against brute force attack by a combination of multiple private keys. Nevertheless, optical encryption schemes based on the polarization properties of light wave could still be vulnerable to known- and chosen- plaintext attacks. Therefore, in this paper, a novel asymmetric polarization encryption method is implemented for dual images, and combined with interference-based optical image encryption method and a Q-plate. First, the information about the two images to be encrypted is separated into two pure phase plates by means of interference optical image encryption, which will be further encoded into two mutually orthogonally polarized light beams. Next, the Q-plate and pixelated polarizer are used for realizing different polarization distributions of the two light beam. Ultimately, the output intensity distribution is recorded by a charge coupled device (CCD) which will be treated as the final ciphertext. For actualizing the asymmetric encryption, one of the pure phase plates acts as a decryption key, which is different from the encryption key. We can control the polarization state of each pixel according to the parameter &lt;i&gt;q&lt;/i&gt;, causing the Q-plate to be electrically controllable and the optic-axis orientation of each pixel to differ from one another. It should be emphasized that the value of &lt;i&gt;q&lt;/i&gt; and the polarization angle of the pixelated polarizer play the role of two encryption keys, which improves the security of the algorithm extremely, due to their high sensitiveness. Theoretical analyses and numerical simulations verify the feasibility and effectiveness of the proposed encryption scheme.

基于频谱融合和柱面衍射的双图像非对称加密

基于频谱融合和柱面衍射的双图像非对称加密

Practice variations in salivary gland imaging and utility of virtual unenhanced dual energy CT images for the detection of major salivary gland stones.

Background There are variations in computed tomography (CT) protocols used for evaluating sialolithiasis, with some protocols including acquisitions before and after IV contrast administration. Dual-energy CT (DECT) can be used to generate virtual unenhanced (VUE) images, potentially precluding the need for an uninfused scan. Purpose In this study, we performed a survey in order to assess variations in the imaging approach for sialolithiasis and evaluated the accuracy of DECT VUE images for the detection of salivary stones. Material and Methods Practice variations were evaluated by an online survey of the membership of the American Society of Neuroradiology. We then identified 28 patients with salivary gland calcifications matched with 28 negative controls that had both an unenhanced and a contrast-enhanced acquisition performed as DECT. A total of 123 major salivary gland calcifications and 85 tonsilloliths were evaluated and the true unenhanced series was used as gold standard. Results The survey revealed substantial variations in CT protocols used for sialolithiasis. On a per-patient basis, DECT VUE had 96.4% sensitivity and 100% specificity. On a per-calcification basis, sensitivity and specificity was 100% for stones &gt; 2 mm but dropped for smaller calcifications. The false-negative cases corresponded to clinically insignificant, intra-glandular parotid calcifications. Inter-reader agreement was excellent (0.9256). Conclusion This study confirms that there are significant variations in CT protocols used for evaluation of sialolithiasis. A single contrast-enhanced DECT acquisition with reconstruction of VUE may represent an attractive, streamlined alternative and enable the elimination of the true unenhanced phase and associated radiation exposure.

Clinical feasibility of optical coherence micro-elastography for imaging tumor margins in breast-conserving surgery.

It has been demonstrated that optical coherence micro-elastography (OCME) provides additional contrast of tumor compared to optical coherence tomography (OCT) alone. Previous studies, however, have predominantly been performed on mastectomy specimens. Such specimens typically differ substantially in composition and geometry from the more clinically relevant wide-local excision (WLE) specimens excised during breast-conserving surgery. As a result, it remains unclear if the mechanical contrast observed is maintained in WLE specimens. In this manuscript, we begin to address this issue by performing a feasibility study of OCME on 17 freshly excised, intact WLE specimens. In addition, we present two developments required to sustain the progression of OCME towards intraoperative deployment. First, to enable the rapid visualization of en face images required for intraoperative assessment, we describe an automated segmentation algorithm to fuse en face micro-elastograms with OCT images to provide dual contrast images. Secondly, to validate contrast in micro-elastograms, we present a method that enables co-registration of en face images with histology of WLE specimens, sectioned in the orthogonal plane, without any modification to the standard clinical workflow. We present a summary of the observations across the 17 specimens imaged in addition to representative micro-elastograms and OCT images demonstrating contrast in a number of tumor margins, including those involved by invasive ductal carcinoma, mucinous carcinoma, and solid-papillary carcinoma. The results presented here demonstrate the potential of OCME for imaging tumor margins.

Polarization-switchable holograms based on efficient, broadband multifunctional metasurfaces in the visible regime.

Gradient metasurfaces provide a novel approach to the phase manipulation of incident electromagnetic waves. Thus, they have the potential to create compact, light-weight optical solutions. An attractive feature of metasurfaces is the ability to integrate multiple optical functionalities into a single surface design. Here we demonstrate a high-efficiency (up to ~60%), reflective meta-hologram for visible light by using an ultra-thin (~λ/4 thick) gap surface plasmon-based metasurface. By precisely sampling the predesigned image phase and amplitude to the unit cells of our device, polarization-controlled dual images are reconstructed with a high polarization extinction ratio and high fidelity. The proposed technique expands the range of possibilities for high-quality hologram generation by using ultra-thin nanophotonic devices and paves the way for variousholography-related applications across the visible band.

Virtual non-enhanced dual-energy CT reconstruction may replace true non-enhanced CT scans in the setting of suspected active hemorrhage

ObjectiveTo assess virtual non-enhanced dual energy computed tomography (DECT) reconstruction as a potential alternative to true non-enhanced thoracic and abdominal CT scans in patients with suspected active hemorrhage. Methods and MaterialsNinety-seven consecutive patients with suspected active bleeding, who underwent routine triphasic CT with intravenous contrast, were included. All patients underwent single energy non-enhanced (TNE) and arterial phase CT as well as venous DECT. Using commercially available software, venous dual energy images were used to generate virtual non-enhanced images (VNE). TNE and VNE were evaluated regarding subjective image quality and diagnostic confidence on a 5-point-scale. The consistency of interpretation with respect to presence and type of hemorrhage between conventional triphasic CT including TNE and biphasic CT with simulated VNE was assessed by two blinded independent readers. ResultsAmong the included subjects (mean age: 66.3 ± 14.5 years, 63.9% male), 37.1% were diagnosed with acute hemorrhage. VNE yielded significantly lower image quality but superior reduction of artefacts as compared to TNE (p ≤ 0.001). Diagnostic confidence was rated high for both TNE and VNE with a significant superiority of TNE (p = 0.003). Triphasic and biphasic CT datasets yielded perfect intrareader agreement regarding presence and type of hemorrhage. The interrater agreement was almost perfect (K = 0.955). Radiation dose was significantly reduced using biphasic dual energy CT with VNE (p ≤ 0.001). ConclusionVirtual non-enhanced images yield comparable diagnostic confidence and perfect agreement with true non-enhanced images for assessment of acute hemorrhage. This suggests that true non-enhanced images could be replaced by virtual non-enhanced images resulting in a significant reduction of radiation dose.

The Real Wolves of Wall Street: Examining Debt, Austerity, and Accountability through the Lens of Primitive Accumulation

ABSTRACTThis article looks debt and austerity as a contemporary form of primitive accumulation. Marx saw that the transition from feudalism to capitalism was accomplished not only by enclosures and the enslavement of peoples of the Americas and Africa; it required an ensemble of ideas and stories that justified these actions. Today’s expropriation by debt also requires public discourses and cultural productions that work in concert with the coercive mechanisms of the state to protect the interests of the rentier class and shift accountability for financial malfeasance to others. It examines the ascendency of neoliberal economic policies in the United States, and then it examines the narratives that accompanied it through three feature films about finance. These films construct dual images of masculinity that portray men as either the “bad boys” of Wall Street, or their obverse, sober and responsible guardians of the financial order. They contribute to a public discourse in which insider trading and stock market manipulations are not, in and of themselves, blameworthy. What is blameworthy is a particular type of failure, and it is this discursive move that allows both the moral culpability and economic consequences of debt to be shifted from the elites to others.