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Color fundamentals for digital imaging
Published in Sharma Gaurav, Digital Color Imaging Handbook, 2017
It is, in fact, possible to draw significantly stronger conclusions from Equations 1.3 and 1.4. One of the characteristics of color vision that can be deduced based on these equations is the phenomenon of trichromacy, which states that it is possible to produce a color match for a given stimulus (equivalently, identical cone responses under the same viewing conditions) by using only combinations of light from three light sources.105,200,201 To establish this, consider three color primaries, i.e., three colorimetrically independent light sources p1, p2, p3. The term colorimetrically independent will be used in this chapter to denote a collection of spectra such that the color of any one cannot be visually matched by any linear combination of the others. Mathematically, colorimetric independence of p1, p2, p3 is equivalent to the linear independence of the three-vectors STp1, STp2, and STp2. Hence, if P = [p1, p2, p3], the 3 × 3 matrix STP is nonsingular.
Light and Color
Published in Abdul Al-Azzawi, Light and Optics, 2018
Normal colour vision is often called trichromat, which refers to a person having the ability to sense or discriminate light from dark, red from green, and yellow from blue. Colour blindness is when an individual is limited in his/her ability to discriminate colour, such as red from green and yellow from blue. If a person has the ability to see contrast from light to dark and cannot discriminate one colour pattern from another, that individual has dichromat vision. If the individual has only the ability to see contrast of light to dark, the person has the vision of a monochromat.
Light and Colour
Published in Abdul Al-Azzawi, Photonics, 2017
Normal colour vision is often called trichromat, which refers to a person having the ability to sense or discriminate light from dark, red from green, and yellow from blue. Colour blindness is when an individual is limited in his/her ability to discriminate colour, such as red from green and yellow from blue. If a person has the ability to see contrast from light to dark and cannot discriminate one colour pattern from another, that individual has dichromat vision. If the individual has only the ability to see contrast of light to dark, the person has the vision of a monochromat.
Impact of Color Matching Primaries on Observer Matching: Part II – Observer Variability
Published in LEUKOS, 2022
Jiaye Li, Peter Hanselaer, Kevin A. G. Smet
A fundamental property of normal human color vision is trichromacy, i.e. that a color match can be found for any light (visual stimulus) by varying the optical power of three primaries. Trichromacy can be characterized by three spectral response functions: color matching functions (CMFs). There are substantial variations in the physiology of individual observers, resulting in different individual CMFs. Therefore, the International Commission for Illumination (CIE) standardized the specification of color by defining CMFs of an average or a standard observer for practical purposes.
Colour forecasting
Published in Textile Progress, 2019
The light sensitive area of the retina in the eye is composed two types of photoreceptor cell, rods and cones. The rods respond to low levels of illumination but do not enable colour vision. It is the cones, which respond to high levels of illumination which enable us to perceive colour. Because there are three types of cone: S, M and L. The shorter colour wavelengths we see (blues/violets) are detected by the S cone type, long wavelengths (reds) are detected by cone type L and cone type M is sensitive to the mid-range wavelengths (greens). With overlap of sensations between the three cone types, humans also perceive the full range of intermediary colours with which we are familiar, and this is known as trichromacy [269]. If one of the cone types is faulty certain wavelengths cannot be detected, and this will affect the way an individual will perceive colour. For example, if cone type S is deficient blue-violet colours are affected, if cone type L is deficient red colours are affected, and if the M cones are deficient green colours are affected. Around 8% of males (around the globe) are believed to have a deficiency of colour. Faulty or missing M cones are most common affecting the experience of reds and greens. Defective L cones can also impact on an individuals’ ability to see red and green colours. In more-rare cases, the S cones are faulty or missing affecting the experience of blues and yellows. Colour deficiency is often incorrectly referred to as colour blindness. Colour blindness only occurs when two cone types are faulty or missing which is extremely rare. Colour experts, often with the exception of forecasters and fashion designers, are commonly tested for colour deficiency (as this negative impact on dyeing and colour matching) and most often the Ishihara test is used [270]. It involves a system of 38 plates wherein on each plate a number or a randomly formed shape appears as a series of coloured dots embedded within a further series of background dots [271]. An example of one of the plates is shown in Figure 7 showing the number 74.