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Cognitive Ergonomics
Published in Prabir Mukhopadhyay, Ergonomics for the Layman, 2019
Design pertinence. The retina is made up of cells called cone cells which help in color perception. Globally, approximately 6% of the male population is red and green color blind, which means they cannot perceive pure red and pure green but instead perceive them in shades of gray. Less than 1% of the female population suffers from such color blindness, so women should be happy! Similarly, elderly people above the age of 60 cannot perceive pure blue and hence perceive it in shades of gray. This is due to the degeneration of the receptive cones for that particular color. Thus, the solution to these problems could be to change the color spectrum from pure to a little impure by mixing in some additives. For example, pure green can be made yellowish green, which is then visible to all. Similarly, pure red can be made amber red. Pure blue can also be made whitish blue. These colors then become visible to all.
Light Sources
Published in Toru Yoshizawa, Handbook of Optical Metrology, 2015
The human eye is not equally sensitive to all the wavelengths of light. The eye is most sensitive to green–yellow light, the wavelength range where the sun has its peak energy density emission, and the eye sensitivity curve falls off at higher and lower wavelengths. The eye response to light and color depends also on light conditions and is determined by the anatomical construction of the human eye, described in detail in Encyclopedia Britannica, 1994. The retina includes rod and cone light receptors. Cone cells are responsible for the color perception of the eye and define the light-adapted vision, that is, the photopic vision. The cones exhibit high resolution in the central part of the retina, the foveal region (fovea centralis), which is the region of greatest visual acuity. There are three types of cone cells, which are sensitive to red, green, and blue light. The second type of cells, the rods, are more sensitive to light than cone cells. In addition, they are sensitive over the entire visible range and play an important role in night vision. They define the scotopic vision, which is the human vision at low luminance. They have lower resolution ability than the foveal cones. Rods are located outside the foveal region, and therefore, are responsible for the peripheral vision. The response of the rods at high-ambient-light levels is saturated and the vision is determined entirely by the cone cells (see also Refs. [5,15]). Photometry is based on the eye’s photopic response, and therefore, photometric measurements will not accurately indicate the perceived brightness of sources in dim lighting conditions.
Colorimetry
Published in John G. Webster, Halit Eren, Measurement, Instrumentation, and Sensors Handbook, 2017
Color vision and perception is complex and has been extensively studied. Ninety-two percent of men and 99.5% of women have “normal” color vision. The eye’s lens focuses images on the light-sensitive retina. Rod cells make up the majority of the retina and are sensitive to low levels of illumination (night vision). Cone cells provide color vision and are located in a small area of the retina called the foveal pit. There are three types of cone cells. One type of cone cells has peak sensitivity to blue light, one type to green light, and one type to red light. Signals from the cone cells are transmitted to the brain where they are processed into color perceptions.
Tunnel vision optimization method for VR flood scenes based on Gaussian blur
Published in International Journal of Digital Earth, 2021
Lin Fu, Jun Zhu, Weilian Li, Qing Zhu, Bingli Xu, Yakun Xie, Yunhao Zhang, Ya Hu, Jingtao Lu, Pei Dang, Jigang You
The main photosensitive capacity of the human eye originates from rod cells and cone cells distributed on the retina. The former are connected to common nerve endings; the latter have the ability to transmit signals to the brain and are concentrated in the fovea of the retina while being more sparsely distributed in peripheral areas, such that the central fovea has the highest sensitivity and resolution (Weier et al. 2016; Bastani et al.2017). The relationship between eye eccentricity (viewing angle) and spatial resolution is shown in Figure 2 (a). Based on the eccentricity, the visual field of the human eye is divided into different horizons, as shown in Figure 2 (b). Generally, for an image reflected on the retina of the human eye, the central part of the eye can clearly distinguish objects only in the range of approximately 15°–20°, which is called the resolved field of view; the range of 20°–30° is called the effective field of view, where the resolution ability is significantly reduced; and the range of 30°–104° is called the induced field of view, where it is necessary to rotate the eyeballs or head to identify scene objects. There are differences in the visual field of human eye resolution between different users, and there are also slight differences between eyes of the same user (Weier et al. 2017; Koulieris et al. 2019). This paper focuses on the human visual characteristics between different users.
Calculation of Mesopic Luminance Using per Pixel S/P Ratios Measured with Digital Imaging
Published in LEUKOS, 2019
Mikko Maksimainen, Matti Kurkela, Pramod Bhusal, Hannu Hyyppä
The human retina consists of cone cells used for accurate day and color vision and rod cells applied for dark vision. Day vision is also called “photopic vision,” and dark vision is called “scotopic vision.” The sensitivity peaks for photopic and scotopic visions are 555 nm and 507 nm, respectively (CIE 1990; Crawford 1949). Thus, scotopic vision is more sensitive to shorter wavelength (bluish) light, and photopic vision is more sensitive to longer wavelength (reddish) light. However, in the luminance range of 0.005–5.0 cd/m2, partly scotopic and partly photopic vision applies (CIE 2010). This region is known as the “mesopic region,” and the vision for this region is mesopic vision. In the CIE 191 system for mesopic photometry, the mesopic sensitivity curve is calculated as follows: