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Principles of Color
Published in Terry A. Slocum, Robert B. McMaster, Fritz C. Kessler, Hugh H. Howard, Thematic Cartography and Geovisualization, 2022
Terry A. Slocum, Robert B. McMaster, Fritz C. Kessler, Hugh H. Howard
The basic features of the eye that concern cartographers are shown in Figure 10.3. After passing through the cornea (a protective outer covering) and the pupil (the dark area in the center of our eye), light reaches the lens, which focuses the light on the retina. Changing the shape of the lens, an automatic process known as accommodation, focuses images. As we age, our lenses become more rigid, and our ability to accommodate thus weakens. Generally, around the age of 45, our ability to accommodate becomes so weak that corrective lenses (glasses or contacts) are necessary. The fovea is the portion of the retina where our visual acuity is the greatest. The optic nerve carries information from the retina to the brain and creates what is commonly termed our blind spot.2
Vision
Published in Anne McLaughlin, Richard Pak, Designing Displays for Older Adults, 2020
Macular degeneration need not be age related, but it is more common in older adults. Those with macular degeneration lose sight in the fovea, the portion of the retina responsible for fine detail and the center of the visual field. It is the leading cause of vision loss and is currently incurable. Causes are not known, but risk factors include smoking and Caucasian heredity. Macular degeneration makes reading or display use difficult because these tasks tend to occur in the central focal area (Figure 2.7). However, the receptors in the periphery are intact, meaning that people with macular degeneration can see peripheral information and respond well to motion (remember that the periphery contains more rods [detecting light and motion] than cones [detecting fine detail and colors]). Design for macular degeneration is not yet common, but certainly possible given fluid display design (Figure 2.8).
Computer and Human Vision Systems
Published in Sheila Anand, L. Priya, A Guide for Machine Vision in Quality Control, 2019
The rods and cones are elongated retinal cells that collect the light that hits the retina. Rod photoreceptors work well in low light, provide black-and-white vision, and detect movements. Cones are responsible for color vision and work best in medium and bright light. There are three types of color-sensitive cones in the retina of the human eye, corresponding roughly to red, green, and blue detectors. The different colors are produced by various combinations of these three types of cones and their photopigments. White light is produced if the three types of cones are stimulated equally. Rods are located throughout the retina, while cones are concentrated in a small central area of the retina called the macula. The macula is yellow in color and absorbs excess blue and ultraviolet light that enters the eye. The macula is responsible for high resolution and therefore gives the eye the capability to discern details. At the center of the macula is a small depression called the fovea, which has the largest concentration of cones. The fovea is responsible for maximum visual activity and color vision. Photoreceptor cells take light focused by the cornea and lens and convert it into chemical and nervous signals which are transported to visual centers in the brain by way of the optic nerve.
Modeling driver behavior in critical traffic scenarios for the safety assessment of automated driving
Published in Traffic Injury Prevention, 2023
Alexandra Fries, Ludwig Lemberg, Felix Fahrenkrog, Marcus Mai, Arun Das
A cognitive processing of visual information is possible by allocating the fovea centralis onto a visual stimulus. The fovea is the (circular) spot of sharpest sight in the center of the retina (line of sight) and is about 2° to 4° wide. Stimuli being presented eccentrically to the line of sight are perceivable in the peripheral field of view (elliptical shape; about 180° wide horizontally and 110° vertically). The quality of extracted information increasingly worsens with further distance between the stimulus and the fovea. However, the periphery is very sensitive toward changes in stimuli (e.g., movement, luminance, color). Therefore, perceived stimuli in the periphery cause an unconscious allocation of the fovea toward them (see e.g., Stapel et al. 2022). These mechanisms are part of the bottom-up (external) control of attention. The counterpart to this is the top-down (internal) control of attention. It is intentionally triggered, when vital information for a task execution is missing or uncertain (e.g., control mirror gazes before a lane change). As especially bottom-up mechanisms are highly relevant for the application in the first scenario presented in this paper (see following section) these mechanisms are further explained subsequently.
A Comprehensive Survey on the Detection of Diabetic Retinopathy
Published in IETE Journal of Research, 2022
The macula is located in the middle area of the retina and is a vital part. It enables a clear vision of objects present in front of the eye. The fovea is a dip in the macula’s centre, where vision is the sharpest. Detection of the macula and fovea is important in the detection of diabetic retinopathy. The image preprocessing is a preliminary step in the detection of macula and fovea. Green channel extraction, data normalization and augmentation are employed on retinal images. Images are annotated pixel-wise for localization of the macula and fovea. The proposed method involves image preprocessing, detection of blood vessels, selection of the region of interest and detection of macula and fovea. Furthermore, the macula is detected by the selection of the region of interest, contrast enhancement and blood vessel removal [62].
Detection of macular diseases in optical coherence tomography image
Published in International Journal of Parallel, Emergent and Distributed Systems, 2020
Xiaoming Liu, Zhou Yang, Wei Hu, Jun Liu, Kai Zhang
According to the anatomical definition of retina around macular regions [25], an OCT image is divided into three zones: fovea (Fovea), parafovea (PA) and perifovea (PE). Pathological change occurs mostly in these three zones. Fovea is about 1.5 mm in diameter, and is located at the centre of macular region. Foveola is the centre of fovea and the diameter is about 0.35 mm. PA is an annular region with 0.5 mm in width around Fovea. PA can be further subdivided into left parafovea (PA_L) and right parafovea (PA_R). PA_L and PA_R are approximately symmetric about Fovea. PE is an annular region with 1.5 mm in width around PA. Similarly, PE can be divided into left perifovea (PE_L) and right perifovea (PE_R). Figure 5 shows the schematic diagram of macular region division. In this paper, all features are calculated in each sub-region, which takes the location of lesion into consideration.