Human eyes have receptors for light of wavelength (called cones).
The wavelengths are divided into short (s), medium (m) and long (L), so in principle, only three parameters can describe colour perception.
The computer colour is the math of light.
Colour space refers to any method of associating each colour with three numbers (or tricolour stimulus values) .
CIE 1931 colour space is one of these colour spaces. CIE 1931 colour space usually gives tricolour stimulus values of colours, which are represented by X, y and Z. CIE XYZ colour space is based on the direct measurement of human colour vision, and serves as the definition basis of many other colour spaces.
RGB is the acronym of red, green and blue“ “RGB colour space” generally refers to “all colours” used in hardware and software. SRGB is a specific type of RGB. SRGB is very popular, but its gamut is very limited. Adobe RGB is a colour space including SRGB and CMYK.
The HSV colour model describes colours in terms of their shade (saturation or amount of grey) and brightness (value). Hue tells the angle to look at the cylindrical disk. The hue represents the colour. The hue value ranges from o to 360 degrees. The saturation value tells us how much quantity of respective colour must be added. A 100% saturation means that complete pure colour is added, while a 0% saturation means no colour is added, resulting in grayscale. The value represents the brightness concerning the saturation of the colour. the value 0 represents total black darkness, while the value 100 will mean a full brightness and depend on the saturation. HSV= (H, S, V). Normal H, S, V: (0-360,0-100%,0-100%).
YIQ model separated chrominance from luminance. Luminance information is contained on the Y-channel, whereas colour information is carried on I and Q channels (in-phase and in-quadrature), in-short YIQ (Luminance, In-phase, Quadrature). Y-channel carries a lot of luminance information.
YIQ colour mode is a colour space conversion mode based on human visual characteristics. It optimises and processes images by adjusting parameters such as brightness and chromaticity. The RGB to YIQ conversion is defined as: [Y] [0.299 0.587 0.114] [R] [I] = [0.596 -0.275 -0.321] [G] [Q] [0.212 -0.523 0.311].
he history of measuring digital colour for computers has been relative slow compare to the development of computer screens. For example, the current mainstream computer colour model RGB in 2024 was originated from the three primary colours theory of vision proposed by Thomas Young in 1809 in the early 20th century. It was not a computer colour model until the 1990s that scientists successfully produced blue LED lights and RGB became popular.
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