What is color really ?

Chain of Action Between Light And Color Sensation

Light (1) reaches an object. A portion of the light is absorbed, eliminated, i.e. transformed into heat (2). The non-absorbed portion, the residual light, is reflected as color stimulus (3) in the observer's eye (4). After completion of the physiological adjustment processes, namely Adaptation, Conversion, and Simultaneous Contrast, an electrical code is generated on the retina for every scanning element and transmitted through the nervous system (5) to the brain. From these colorless data the multicolored three-dimensional field of vision is built as consciousness (6).

From Light to Color Sensation as Consciouness


Light is energy radiation. These energy rays are electromagnetic vibrations of different wavelengths. The length of a wave (frequency) is the distance between two wave crests. There exists a continuous scale of energy rays ranging from fractions of a nanometer up to kilometers, e.g.: gamma rays, alpha rays, X-rays, light, thermal rays, television, radio, electric current. All these energy rays differ from one another only by their wavelengths. We call energy rays in the range of approximately 400 to 700 nm " light " as we think we can see them. Actually, they are only recorded by our visual organ and converted into organ-intrinsic electric pulses.

Light rays are colorless energy rays. Light has no color at all.


It is common knowledge that matter consists of atoms. As atoms unite and form a variety of molecules, different types of material come into being. According to their molecular structure material is able to absorb, i.e. eliminate a portion of the incident light. The non-absorbed portion is reflected, called the Residual Light. The residual light, entering the observer's eye, is called Color Stimulus.

The color stimulus, too, is colorless energy radiation.

Incident sunlight on a green leaf.

The reflected portion of light which enters the observer's eye as color stimulus. The color stimulus is residual light.

Color Stimulus

The wavelengths of a visible spectrum can be present in the color stimulus in many different intensities. This is called spectral distribution.

Which color we see depends on the spectral composition of the color stimulus.

Registration in the Eye

The color stimulus is projected from the outside through the eye's optical system onto the retina. In the retina are embedded tiny photoreceptor cells, called cones and rods.

The photoreceptor cells convert the electric energy of the color stimulus into organ-intrinsic energy pulses forming an electric code.

Correction Mechanisms of the Visual Organ

The code formed by the photoreceptor cells which finally leads to the color sensation does not linearly correspond to the spectral intensities of the color stimulus. The visual organ possesses various correction mechanisms to adapt itself perfectly to the prevailing light and viewing conditions. In case of high light intensity the iris of the eye closes, thus reducing the overall intensity of the color stimulus. This process is called Adaptation. The adjustment to the spectral composition of light is called Conversion. And when the appearance of a color is modified due to the presence of surrounding colors, this is called Simultaneous Contrast. Only after completion of these adjustment processes, the organ-intrinsic electric code is created which finally produces the color sensation.

Nerve Tracts

This electric code is carried to the brain by the nervous system. The photoreceptor cells on the retina are connected in a very complex manner via ganglion cells to the brain.

Strictly speaking, also this code is still colorless.

Color Sensation as Consciousness

As soon as this code reaches the brain, the visual organ converts it into a color sensation. For each image spot on the retina a code is created which leads to the corresponding color sensation. The visual organ is an incredibly complex and admirable instrument. From every single spot on the retina a continuous data string is flowing to the brain where the multicolored picture is composed.

Until today nobody really knows exactly how these data are converted in the brain into a three-dimensional multicolored field of vision.

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