PROPERTIES OF COLOR

Colour is something which makes the object more appealing, attractive and gives the pleasure of observation. The Committee on Colorimetry of Optical Society of America defines colour as visual sensation arising from the stimulation of retina of the eye. Thus it is defined as a psychophysical-psychological response to a physical stimulus.

Colour may have different meanings to different people. To a chemist it may be a chemical compound, a dye or a pigment; to a physicist it is scattering and absorption of light or reflectance spectra of the object; to a physiologist it is a measurable activity of nerves, to a psychologist it is a complex process in brain of interpreting the nerve signal. To the artist and others it is a means to create sensation in the mind of the observer. For e.g., the colours as red and yellow create the sensation of warmth. Green and blue are associated with the feeling of coolness. Colour harmony in wall paints; curtains and furniture make room cheerful, and comfortable.

PERCEPTION OF COLOR

 Perception of colour includes source of light, object that is illuminated and eye and brain that perceive the colour. A source of light is characterised by the energy that is radiated at different wavelengths, i.e., by its spectral power distribution.

The modification of incident radiations depends on the nature of colourants in object. This is related to chemistry of dyes. The radiant energy reflected is absorbed by photosensitive pigments in retina of the eye. The photosensitive detectors on retina are called as rods and cones from their shape. The rods detect the light but have no ability to specify the colour. The colour is detected by cones. 

THREE PROPERTIES OF COLOR:

Hue

When asked to identify the color of an object, you’ll most likely speak first of its hue. Quite simply, hue is how we perceive an object’s color — red, orange, green, blue, etc. The color wheel in Figure 1 shows the continuum of color from one hue to the next. As the wheel illustrates, if you were to mix blue and green paints, you would get bluegreen. Add yellow to green for yellow-green, and so on.

Chroma

Chroma is how bright the color appears, or  how close the color is to either gray or the pure hue. For example, think of the appearance of a tomato and a radish. The red of the tomato is vivid, while the radish appears duller.

Figure 2 shows how chroma changes as we move from center to the perimeter. Colors in the center are gray (dull) and become more saturated (vivid) as they move toward the perimeter. Chroma also is known as saturation .

            

LIGHTNESS

In simple words how close the color is to the black or white, and how much light is reflected from the color. We know that black absorb nearly 100% light and whie reflects nearly 100% light. The scale b/w them is lightness or darkness scale. For example, when a tomato and a radish are placed side by side, the red of the tomato appears to be much lighter. In contrast, the radish has a darker red value.