Artificial Vision System on Digital Devices for Real-Time Head Tilt Control.

It is common to see cases in which, when performing tasks in close vision in front of a digital screen, the posture or position of the head is not adequate, especially in young people; it is essential to have a correct posture of the head to avoid visual, muscular, or joint problems. Most of the current systems to control head inclination require an external part attached to the subject's head. The aim of this study is the validation of a procedure that, through a detection algorithm and eye tracking, can control the correct position of the head in real time when subjects are in front of a digital device. The system only needs a digital device with a CCD receiver and downloadable software through which we can detect the inclination of the head, indicating if a bad posture is adopted due to a visual problem or simply inadequate visual-postural habits, alerting us to the postural anomaly to correct it.The system was evaluated in subjects with disparate interpupillary distances, at different working distances in front of the digital device, and at each distance, different tilt angles were evaluated. The system evaluated favorably in different lighting environments, correctly detecting the subjects' pupils. The results showed that for most of the variables, particularly good absolute and relative reliability values were found when measuring head tilt with lower accuracy than most of the existing systems. The evaluated results have been positive, making it a considerably inexpensive and easily affordable system for all users. It is the first application capable of measuring the head tilt of the subject at their working or reading distance in real time by tracking their eyes.

Measuring High Dynamic Range Spectral Reflectance of Artworks through an Image Capture Matrix Hyperspectral Camera.

Commercial hyperspectral imaging systems typically use CCD or CMOS sensors. These types of sensors have a limited dynamic range and non-linear response. This means that when evaluating an artwork under uncontrolled lighting conditions and with light and dark areas in the same scene, hyperspectral images with underexposed or saturated areas would be obtained at low or high exposure times, respectively. To overcome this problem, this article presents a system for capturing hyperspectral images consisting of a matrix of twelve spectral filters placed in twelve cameras, which, after processing these images, makes it possible to obtain the high dynamic range image to measure the spectral reflectance of the work of art being evaluated. We show the developed system and describe all its components, calibration processes, and the algorithm implemented to obtain the high dynamic range spectral reflectance measurement. In order to validate the system, high dynamic range spectral reflectance measurements from Labsphere's Spectralon Reflectance Standards were performed and compared with the same reflectance measurements but using low dynamic range images. High dynamic range hyperspectral imaging improves the colorimetric accuracy and decreases the uncertainty of the spectral reflectance measurement based on low dynamic range imaging.

Air shooting competition effects on visual skills depending on the sport level.

Olympic shooting is a sport with high demands of accuracy. Minimal visual errors could be related to performance losses. However, not all visual skills have been studied in depth in this sport. The main objectives of this study were to compare differences in shooters' visual skills by level and to analyze the competition effect on them. Sixty-six participants were distributed in three groups (non-athletes, elite and non-elite). Eleven visual variables were tested in four skills groups (visual acuity, heterophoria, accommodation functions and other visual skills). The data were collected through a pre- and post-competition simulation test. The results of the study showed differences between groups by shooting sport level. In general, shooters had higher visual acuity values than non-athletes p < .001 with large size effects (d between 1.01 and 2.35), and elite shooters presented higher values of accommodation than non-elite shooters p < .05 with large size effects (d between 0.88 and 0.97). Furthermore, different visual skills were modified after competition depending on the shooting level. Specifically, visual accommodation skills were only improved in elite shooters. Finally, our study suggests that elite shooters employ different visual strategies or skills to non-elite shooters and that shooting activity is closely related to some specific visual skills. This aspect should be considered by coaches in the design of optimal visual trainings and improve the shooters' performance.Highlights Shooters showed better acuity skills than non-athletes.Shooting activity seems to improve visual acuity skills, binocular visual time and eye-hand coordination in non-elite shooters, and accommodation and eye-hand coordination in elite shooters immediately after the competition simulation.Elite shooters employ different visual strategies or skills to non-elite shooters.Non-dominant eye occlusion may benefit binocular vision recovery by inhibiting aiming action and the use of accommodative flexibility could be related to the QE during the shot.

Hyperparabolic concentrators.

We present a family of three-dimensional concentrators constructed from the photic field generated by a Lambertian emitter. The profile of these concentrators is obtained from the field lines for a two-dimensional truncated wedge and is based on the union between a hyperbola and a tilted parabola. By revolution of this profile, we obtain hyperparabolic concentrators (HPCs). In the limiting case when the focal length of the hyperbola becomes the radius of the exit aperture, the HPC becomes the well-known compound parabolic concentrator. On the other hand, when the focal length of the hyperbola becomes infinite, the HPC achieves the thermodynamic limit of concentration.