Field curvature correction in video endoscope lenses through the parameters of air meniscus

The research presents a method to synthesize lens data of an air meniscus built into the optical layout and acting as a correction element that fixes the field curvature of the entire optical system. The practical application of the proposed method is relevant when creating miniature lenses for medical video endoscopes when a small number of lenses and a flat image field for a CCD/CMOS sensor are important. Analytical dependencies for the lens data of the air meniscus are obtained and significant conditions for the field curvature correction are formed. A numerical example of a front stop lens design is demonstrated and confirms the correctness of the formulated conditions. A comparison of the aberration values of the original lens and an upgraded system is carried out. It is shown that, the values of the field curvature and astigmatism have been compensated as a result of introducing the synthesized parameters of the air meniscus into the optical layout. The correction is achieved while keeping the values of coma, distortion, focal length, and optical system total length at the level of the initial values.

Identity convergence in the tapestry and painting of Ecaterina Ajder

Ecaterina Ajder, representative of the early `80s of plastic artists from the Republic of Moldova, constantly opts for endowing the work of art with innovative stylistic values. Plastic tradition and modernity originally connect in her creation, contributing to the generation of current messages through image. Preferring to materialize her thematic and plastic predilections in the genre of artistic tapestry and easel painting, Ecaterina Ajder has drawn and consolidated over the decades her unmistakable stylistic facet, in which the insurmountable landmarks of folk art have found a favorable artistic fulfillment and integration into relevant contemporary creative trends. In the artistic tapestry, the painter significantly capitalized both the aesthetic expressions obtained from the classic weaving, and from combining it with various techniques such as felt and embroidery. When referring to the easel painting she highlighted the traditional aspects of structural-constructive constitution of the image field and, at the same time, the impressive artistic expressions, obtained after practicing mixed techniques, giving priority to the collage methodology. In the artist’s creation, both the conceptualization and aesthetic interpretation of the theme, as well as the way of operating with plastic means imminently contribute to the demarcation and supplementing of the semantic area of the work with high value expressions.

Posterior vitreous detachment and paravascular retinoschisis in highly myopic young patients detected by ultra-widefield OCT

The purpose of this study was to determine the relationship between a posterior vitreous detachment (PVD) and retinoschisis (RS) in 73 highly myopic (HM) young patients age 16.4 ± 6.9 years and 24 non-HM children age 8.4 ± 1.5 years. The presence of the paravascular retinal abnormalities was determined in the images obtained by a ultra-widefield OCT (UWF OCT) instrument with an image field of 23 × 20 mm. The results showed that a partial PVD was detected in 15 (21%) of the HM patients, and the number increased significantly with increasing age (P = 0.02). PVDs of any type were not found in the non-HM eyes. The number of microvascular folds also increased with age in the HM patients (P = 0.03). Medium-reflective columnar tissues were present between the detached vitreous and inner retinal surface in 4 (5%) eyes of the HM patients. Myopic RS was found in 3 (4%) HM patients in the paravascular area but not in the macular area. These results suggest that early partial PVD may play a role in pathological and proliferative vitreous changes of HM eyes. An intense vitreoretinal traction with bridging tissues may cause the various paravascular retinal abnormalities. In HM eyes, paravascular RS is already present at an early age which may progress to macular RS with aging.

Posterior Vitreous Detachment and Paravascular Retinoschisis in Highly Myopic Young Patients Detected by Ultra-Widefield OCT

The purpose of this study was to determine the relationship between a posterior vitreous detachment (PVD) and retinoschisis (RS) in 73 highly myopic (HM) young patients and 24 non-HM children. The presence of the paravascular retinal abnormalities was determined in the images obtained by a ultra-widefield OCT (UWF OCT) instrument with an image field of 23 x 20 mm. The results showed that a partial PVD was detected in 15 (21%) of the HM patients, and the number increased significantly with increasing age (P=0.02). PVDs of any type were not found in the non-HM eyes. The number of microvascular folds also increased with age in the HM patients (P=0.03). Medium-reflective columnar tissues were present between the detached vitreous and inner retinal surface in 4 (5%) eyes of the HM patients. Myopic RS was found in 3 (4%) HM patients in the paravascular area but not in the macular area. These results suggest that early partial PVD may play a role in pathological and proliferative vitreous changes of HM eyes. An intense vitreoretinal traction with bridging tissues may cause the various paravascular retinal abnormalities. In HM eyes, paravascular RS is already present at an early age which may progress to macular RS with aging.

Method for optimizing the errors of the wavefront of recorded radiation for large-size information-measuring optical systems

The article proposes a new method for increasing the information content of the image by minimizing the errors of the optical system of a large telescope using the redistribution of errors over the image field. Variation of the parameters of the secondary mirror is carried out to solve the optimization problem of uniform distribution of aberrations over the image field of a large telescope using the example of a cryotelescope with a diameter of 12 m in the Zemax-EE package. The results of calculations of optical schemes by the traditional method and by the method of optimization of the errors of the radiation wavefront are presented. The advantages and disadvantages are considered.

Edge-Based Color Image Segmentation Using Particle Motion in a Vector Image Field Derived from Local Color Distance Images

This paper presents an edge-based color image segmentation approach, derived from the method of particle motion in a vector image field, which could previously be applied only to monochrome images. Rather than using an edge vector field derived from a gradient vector field and a normal compressive vector field derived from a Laplacian-gradient vector field, two novel orthogonal vector fields were directly computed from a color image, one parallel and another orthogonal to the edges. These were then used in the model to force a particle to move along the object edges. The normal compressive vector field is created from the collection of the center-to-centroid vectors of local color distance images. The edge vector field is later derived from the normal compressive vector field so as to obtain a vector field analogous to a Hamiltonian gradient vector field. Using the PASCAL Visual Object Classes Challenge 2012 (VOC2012), the Berkeley Segmentation Data Set, and Benchmarks 500 (BSDS500), the benchmark score of the proposed method is provided in comparison to those of the traditional particle motion in a vector image field (PMVIF), Watershed, simple linear iterative clustering (SLIC), K-means, mean shift, and J-value segmentation (JSEG). The proposed method yields better Rand index (RI), global consistency error (GCE), normalized variation of information (NVI), boundary displacement error (BDE), Dice coefficients, faster computation time, and noise resistance.

A System for the Detection of Persons in Intelligent Buildings Using Camera Systems—A Comparative Study

This article deals with the design and implementation of a prototype of an efficient Low-Cost, Low-Power, Low Complexity–hereinafter (L-CPC) an image recognition system for person detection. The developed and presented methods for processing, analyzing and recognition are designed exactly for inbuilt devices (e.g., motion sensor, identification of property and other specific applications), which will comply with the requirements of intelligent building technologies. The paper describes detection methods using a static background, where, during the search for people, the background image field being compared does not change, and a dynamic background, where the background image field is continually adjusted or complemented by objects merging into the background. The results are compared with the output of the Horn-Schunck algorithm applied using the principle of optical flow. The possible objects detected are subsequently stored and evaluated in the actual algorithm described. The detection results, using the change detection methods, are then evaluated using the Saaty method in order to determine the most successful configuration of the entire detection system. Each of the configurations used was also tested on a video sequence divided into a total of 12 story sections, in which the normal activities of people inside the intelligent building were simulated.

Proper collimation effect on radiation dose and image quality in thoracic spine radiography

The purpose of this research was to determine the impact of collimation in thoracic spine radiography on patient exposure and image quality. The study was performed on 84 patients referred to thoracic spine radiography. Patients were randomly divided into two equal groups of 42. The first group was imaged according to the standard collimation protocol used in one of the hospitals in Croatia while the second group was imaged by applying ?optimal? collimation, image field size was individually collimated for each patient or according to the greatest image field collimation depicted in professional literature. For each patient body mass index, image field size, exposure conditions and dose area product were noted and absorbed doses by organs were calculated, image quality was assessed. There were no statistically significant differences in BMI between the two groups of patients. With the optimal collimation the size of the imaging field in the anteroposterior projection was reduced by 45 % ( p < 0.001) and in the lateral projection by 41 % (p < 0.001). The study also showed reduced values of DAP for anteroposterior projection by 34 % ( p = 0.007) and for lateral projection by 23 % ( p = 0.040). The mean absorbed dose to the selected organs decreased by 26 % in the anteroposterior projection and by 28 % in the lateral projection. In addition, the optimal collimation protocol improved image quality by 13 % in anteroposterior projection. No differences in image quality were found in lateral projection. By carrying out this research we have demonstrated that optimal collimation in thoracic spine imaging has a strong influence on patient exposure to radiation and has a positive impact on image quality.