Dr. N.L. Kachhara
Colour is the perception of the frequency (or wavelength) of light. It is a perception, which in humans derives from the ability of the fine structures of the eyes to distinguish (usually three) differently filtered analyses of a view. The full spectrum of the incoming radiation from an object determines the visual appearance of that object, including its perceived colour. A surface that diffusely reflects all wavelengths equally is perceived as white, while a dull black surface absorbs all wavelengths and does not reflect. Though the exact status of colour is a matter of current philosophical dispute, colour is arguably a psychophysical phenomenon that exists only in our minds. A "red" apple does not give off "red light', and it is misleading to think of things that we see, or of light itself, as objectively coloured at all. Rather, the apple simply absorbs light of various wavelengths shining on it to different degrees, in such a way that the unabsorbed light, which it reflects, is perceived as red. An apple is perceived to be red only because normal human colour vision perceives light with different mixes of wavelength differently and we have language to describe that difference.
Most light sources are not pure spectral sources; rather they are created from mixtures of various wavelengths and intensities of light. To the human eye, however, there is a wide class of mixed spectrum light that is perceived the same as a pure spectral colour. An apple, which is perceived as red with spectrum sources, may be perceived to have a different colour with a light source, which is at variance with spectral source.
Although Aristotle and other ancient scientists speculated on the nature of light and colour vision, it was not until Newton that light was correctly identified as the source of colour sensation. Goethe studied the theory of colours, and in 1801 Thomas Young proposed his tri chromatic theory, which was later, refined by Hermann von Helmhotz. That theory was confirmed in 1960s. In 1931, an international group of experts called the Commission International d Eclairage (CIE) developed a mathematical colour model. The premise used by the CIE is that colour is the combination of three things a light source, an object, and an observer.
A light wave can be analyzed as a superposition of sine waves, each of which has a specific frequency and wavelength. Electromagnetic radiation is a mixture of radiation of different wavelengths and intensities. When this radiation has a wavelength inside the human visibility range (approximately from 380 nm to 740 nm), it is known as light within the (human) visible spectrum. The light's spectrum records each wavelength's intensity. The full spectrum of the incoming radiation from an object determines the visual appearance of that object, including its perceived colour. The intensity of a spectral colour may alter its perception considerably. The colours of the visible light spectrum are red, orange, yellow, green, cyan, blue and violet. In addition to these spectral colours there are many colour perceptions that by definition cannot be pure spectral colours. Some example of necessarily non-spectral colours is the achromatic colours (black, gray and white) and others colour such as pink, tan and magenta. The perception of colour is influenced by biology, long-term history of the observer, and also short-term effects such as colour nearby.
The retina of the human eye contains three different types of colour receptor cells or cones. (i) The S-cones, called short wavelength cones are most responsive to light that we perceive as violet, with wavelengths around 420 nm, (ii) The L-cones, called long wavelength cones, are most sensitive to light we perceive as yellowish green with wavelengths around 564 nm, and (iii) The M-cones, the middle wavelength cones, are most sensitive to light perceived as green, with wavelengths around 534 nm. The sensitivity curves of the cones are roughly bell-shaped, and overlap considerably. The incoming signal spectrum is thus reduced by the eye to three values, sometimes called tri stimulus values, representing the intensity of the response of each of the cone types. The set of all possible tri stimulus values determine the human colour space. It has been estimated that humans can distinguish roughly 10 million different colours, although the identification of a specific colour is highly subjective, since even the two eyes of a single individual perceive colours slightly differently. A mixture of three colours called primaries can generate most human colour perceptions. These primary colours are red, blue and green.
According to Jain philosophy, matter, as aggregate or paramanu, has the qualities of touch, taste, odour and colour. Being objective reality, these qualities do not depend on the observer. An observer may or may not perceive the object in its true state due to inability or limitation of his sense organs or sensing system but this does not alter the nature of the object. An object is composed of infinite number of paramanus and it has all the colours. But when we see the object we do not perceive all the colours. For instance, a parrot has all the colours but we perceive only the green colour. This is due to limitation of our sense organ. An observer possessing superlative powers may see all the colours of parrot. In other words, from the absolute point of view (nischaya naya) the parrot has all the five colours and from practical point of view (vyavhar naya) its colour is green. The observer and the subject are independent having separate existence and the observer does not influence the nature of the subject. Similarly, truly speaking, the grass is not green, it has all the colours. The number of paramanus having green colour are more than the paramanus of any other colour and therefore we see the grass as green.
The Jain and scientific point of views are similar in some respect, as both believe that the colour is a quality of the object. What radiations of the incident light are absorbed depends on the characteristic of the object. Science offers no explanation for why certain radiations are absorbed and an object reflects other radiations. Science can answer this question only when the true nature of the matter has been understood. According to Jain philosophy colour etc. are objective realities of matter and these cannot be truly perceived by physical senses.
