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Lamp Measurement and Characterization
Published in M. Nisa Khan, Understanding LED Illumination, 2013
The human eye photoreceptors, or cone cells, have been shown to have sensitivity peaks in red, green, and blue wavelength regions in the presence of medium- and high-brightness ambient light (i.e., there are three primary color stimuli for photopic vision). Therefore, in principle, all colors may be expressed by means of some appropriate tristimulus value representation. Color spaces, including the CIE 1931 XYZ and CIE 1964, associate tristimulus values with colors and thereby provide the means to quantify color properties of objects and light sources. The interested reader is encouraged to learn more about color spaces and matching functions in relation to describing and quantifying colors from numerous available publications including those from CIE [84,85].
Electrochromism in Conjugated Polymers – Strategies for Complete and Straightforward Color Control
Published in John R. Reynolds, Barry C. Thompson, Terje A. Skotheim, Conjugated Polymers, 2019
Anna M. Österholm, D. Eric Shen, John R. Reynolds
Because the perception of color varies between individuals, and because commercial demands can place strict requirements on color precision, it is important to be able to quantify the exact hue of a specific color. The human eye has three types of cone cells that are sensitive to various wavelength ranges of light; if the total light power spectrum is weighted to account for this spectral sensitivity, we generate three effective stimulus values that objectively quantify a color. The science behind colorimetry was extensively developed by Commision Internationale de l’Eclairage (CIE).
Optical Systems and Components
Published in Araz Yacoubian, Optics Essentials, 2018
For example, the human eye manipulates light using a lens that focuses light and images from the scene onto a biological photodetector array (retina). The detector converts light to a signal that is sent to the brain for processing and interpreting.
Eye Tracking, Usability, and User Experience: A Systematic Review
Published in International Journal of Human–Computer Interaction, 2023
Jakub Štěpán Novák, Jan Masner, Petr Benda, Pavel Šimek, Vojtěch Merunka
Eye tracking is a technology of tracking a person’s eye movement to determine where they are looking, for how long, and how the eye got there. Eye tracking systems analyze the user’s eye location, movement, and pupil size at a specified moment to determine areas of interest (Hasse & Bruder, 2015). Many studies involve eye trackers, including visual systems, psychology, neurology, and virtual reality (McNamara & Mehta, 2020). Essential usable components of the human eye for eye tracking technology are the retina, pupil, cornea, sclera, and iris (Hansen & Ji, 2010). The activity of these components can be recorded as signals and utilized in many applications (Annerer-Walcher et al., 2021). Eye detection is the process of locating the eye and measuring the eye gaze. Several methods are used for gaze tracking, such as shape, feature, appearance, and hybrid-based methods (Hansen & Ji, 2010). There are numerous eye tracking devices on the market—from glasses to specialized bars that can be mounted to monitors and other devices or placements. The primary mechanism of these devices is based on an infrared non-visible light beam pointing to subjects’ face and eyes. This approach aims to recognize two core reference elements. The first is the reflection of retinal light, and the second is the reflection of light in the cornea (Chivu et al., 2018).
Wavefront aberrations caused by biomechanical effects after Small Incision Lenticule Extraction (SMILE) based on finite element analysis
Published in Computer Methods in Biomechanics and Biomedical Engineering, 2023
Yinyu Song, Lihua Fang, Qianwei Liu, Jiahui Gong, Binhui Guo
The same structural data and material parameters were used for the 3D human eye model, avoiding the influence of personalized eyeball parameters on experimental data. Then the method of quantitative analysis was used to explore the effects of diopter, IOP, and the incision size on wavefront aberrations. In addition, the factors of influencing residual wavefront aberrations may include decentration, corneal ablating depth, etc. Therefore, the same method was used to carry out the exploration of refractive surgery, which not only saved costs, but also provided specific theoretical support for SMILE refractive surgery. However, there are some limitations in our study. First, the cornea and sclera of the human eye were considered, but the influence of other components were not considered. Second, the material properties of the sclera and corneal tissues were fundamental to the induced wavefront aberrations. Our model used the Ogden function to represent the nonlinear material properties of the models. In clinical practice, the eye material parameters have significant individual differences. The influence of these aspects was worth further exploration.
A New Design of Iris Recognition Using Hough Transform with K-Means Clustering and Enhanced Faster R-CNN
Published in Cybernetics and Systems, 2022
Gorla Babu, Abdul Khayum Pinjari
Iris recognition is a biometric identification and verification technique, which authenticates a human through an image of a person’s eye that is used for more accurate analysis because of the high entropic iris patterns (Liu et al. 2020). Iris is a circular membrane, which is located among the lens and the cornea of the human eye, which aims for controlling the amount of light crossing with the pupil by relaxing and contracting the dilator muscles and the pupillary sphincter (Labati et al. 2020). Due to the unique and invariant features of the human iris texture of each person, it is robust for using it in identification systems (Shuai et al. 2020). The major factors for developing an iris recognition model are the durability of the iris structure in the human’s lifetime, the unique pattern of the iris, and the user-friendly image attained by devices with a broad range of improved abilities that promotes biometric identification among the public (Proença and Neves 2018). Pattern recognition and computer vision sectors are the major efficient fields, which prevent diverse issues in multiple aspects. In recent years, with the progressions in technology particularly in biometrics, features have been promoted to get protection around the world (Trokielewicz, Czajka, and Maciejewicz 2020; Lin, Liu, and Chen 2009).