Editorial to the Special Issue "Vision Sensors: Image Processing Technologies and Applications".

Computer vision and optical technologies have become attractive alternatives for metrology, chemical analysis, and non-destructive structural health monitoring and the evaluation of aerospace, civil, and mechanical engineering structures [...].

Using Conventional Cameras as Sensors for Estimating Confidence Intervals for the Speed of Vessels from Single Images.

In this paper, we describe an image-based approach for estimating the speed of a moving vessel using the wakes that remain on the surface of water after the vessel has passed. The proposed method calculates the speed of the vessel using only one RGB image. In this study, we used the vanishing line of the mean water plane, the camera height concerning the level of the tide, and the intrinsic parameters of the camera to perform geometric rectification on the surface plane of the water. We detected the location of troughs on one of the wake arms and computed the distance between them in the rectified image to estimate the speed of the vessel as a so-called inverse ship wake problem. We used a radar that was designed to monitor ships to validate the proposed method. We used statistical studies to determine the reliability and error propagation of the estimated values throughout the calculation process. The experiments showed that the proposed method produced precise and accurate results that agreed with the actual radar data when using a simple capture device, such as a conventional camera.

An Augmented Reality Periscope for Submarines with Extended Visual Classification.

Submarines are considered extremely strategic for any naval army due to their stealth capability. Periscopes are crucial sensors for these vessels, and emerging to the surface or periscope depth is required to identify visual contacts through this device. This maneuver has many procedures and usually has to be fast and agile to avoid exposure. This paper presents and implements a novel architecture for real submarine periscopes developed for future Brazilian naval fleet operations. Our system consists of a probe that is connected to the craft and carries a 360 camera. We project and take the images inside the vessel using traditional VR/XR devices. We also propose and implement an efficient computer vision-based MR technique to estimate and display detected vessels effectively and precisely. The vessel detection model is trained using synthetic images. So, we built and made available a dataset composed of 99,000 images. Finally, we also estimate distances of the classified elements, showing all the information in an AR-based interface. Although the probe is wired-connected, it allows for the vessel to stand in deep positions, reducing its exposure and introducing a new way for submarine maneuvers and operations. We validate our proposal through a user experience experiment using 19 experts in periscope operations.

Tooth injuries: Knowledge of parents of public school students from the city of Alfenas, Minas Gerais, Brazil.

BACKGROUND/AIMS: The prognosis of traumatized teeth can be optimized if appropriate procedures are following at the time of the accident. The aim of this study was to evaluate the level of knowledge of students' parents from a group of Brazilian schools regarding fracture and tooth avulsion in permanent teeth. METHODS: Parents of 802 students were interviewed using a pre-tested questionnaire designed to explore how they would manage their child's dental avulsion or fracture. RESULTS: Among the parents, 8.6% reported their child had already suffered tooth injuries. Concerning dental fracture, 49.5% considered the possibility of bonding the tooth fragment and, for dental avulsion, 65.5% considered tooth replantation. Approximately 33.5% of parents would take the child to the dental office in case of fracture or dental avulsion, and of those, 66.2% would do so immediately. Further, 69.5% (for fracture) and 70.4% (for avulsion) would do so regardless of symptoms; only 24.2% and 21.3%, respectively, would seek care only if there was pain. In case of avulsion, 22.3% of those interviewed would store the tooth in liquid, such as saline solution (17.8%), water (16.4%) and fresh milk (12.2%). CONCLUSION: Parents had partial and insufficient knowledge as to the proper approach to be adopted in cases of fracture and dental avulsion. Previous experience of dental trauma was not related to more appropriate behavior regarding these injuries.

A physiologically-based model for simulation of color vision deficiency.

Color vision deficiency (CVD) affects approximately 200 million people worldwide, compromising the ability of these individuals to effectively perform color and visualization-related tasks. This has a significant impact on their private and professional lives. We present a physiologically-based model for simulating color vision. Our model is based on the stage theory of human color vision and is derived from data reported in electrophysiological studies. It is the first model to consistently handle normal color vision, anomalous trichromacy, and dichromacy in a unified way. We have validated the proposed model through an experimental evaluation involving groups of color vision deficient individuals and normal color vision ones. Our model can provide insights and feedback on how to improve visualization experiences for individuals with CVD. It also provides a framework for testing hypotheses about some aspects of the retinal photoreceptors in color vision deficient individuals.

New Methods for Morphological Erythrocytes Classification.

Specialists may gauge the severity of sickle cell disease crisis by quantifying the number of abnormal-looking and sickle-shaped erythrocytes in blood smears. State-of-the-art integral geometry-based descriptors for automatic classification of erythrocytes as normal cells, sickle cells or cells with other deformations have achieved excellent results. Unfortunately, they are computationally expensive, requiring powerful desktop computers and a great deal of memory to run. We propose two new integral geometry-based descriptors for the shape of erythrocytes. Like state-of-the-art techniques, the overall sensitivity of our solutions is above 94%. Nevertheless, our descriptors are designed to avoid a great amount of computation in comparison to similar solutions and to present a lower memory footprint. Our descriptors offer a high specificity of normal cells and a high sensitivity of deformed cells, making them a good alternative in clinical applications.

An efficient naturalness-preserving image-recoloring method for dichromats.

We present an efficient and automatic image-recoloring technique for dichromats that highlights important visual details that would otherwise be unnoticed by these individuals. While previous techniques approach this problem by potentially changing all colors of the original image, causing their results to look unnatural to color vision deficients, our approach preserves, as much as possible, the image's original colors. Our approach is about three orders of magnitude faster than previous ones. The results of a paired-comparison evaluation carried out with fourteen color-vision deficients (CVDs) indicated the preference of our technique over the state-of-the-art automatic recoloring technique for dichromats. When considering information visualization examples, the subjects tend to prefer our results over the original images. An extension of our technique that exaggerates color contrast tends to be preferred when CVDs compared pairs of scientific visualization images. These results provide valuable information for guiding the design of visualizations for color-vision deficients.