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Color vision, a feature of visual perception, is an ability to perceive differences between light composed of different frequencies independently of light intensity.
Visual perception is the ability to interpret the surrounding environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in the visible spectrum reflected by objects in the environment.
Night vision is of lower quality than day vision because it is limited in resolution and colors cannot be discerned; only shades of gray are seen. [1] In order for humans to transition from day to night vision they must undergo a dark adaptation period of up to two hours [ 2 ] in which each eye adjusts from a high to a low luminescence "setting ...
A specific type of NVD, the night vision goggle (NVG) is a night vision device with dual eyepieces. The device can utilize either one intensifier tube with the same image sent to both eyes, or a separate image intensifier tube for each eye. Night vision goggles combined with magnification lenses constitutes night vision binoculars.
On average, there are approximately 92 million rod cells (vs ~6 million cones) in the human retina. [1] Rod cells are more sensitive than cone cells and are almost entirely responsible for night vision. However, rods have little role in color vision, which is the main reason why colors are much less apparent in dim light.
While color vision is dependent on many factors, discussion of the evolution of color vision is typically simplified to two factors: the breadth of the visible spectrum (which wavelengths of light can be detected), and; the dimensionality of the color gamut (e.g. dichromacy vs. tetrachromacy).
It is known that the rod cells are more suited to scotopic vision and cone cells to photopic vision, and that they differ in their sensitivity to different wavelengths of light. [ 2 ] [ 3 ] It has been established that the maximum spectral sensitivity of the human eye under daylight conditions is at a wavelength of 555 nm , while at night the ...
A night-vision device (NVD), also known as a night optical/observation device (NOD) or night-vision goggle (NVG), is an optoelectronic device that allows visualization of images in low levels of light, improving the user's night vision.