Spreading with harmony

A bit of physics and Biology: The 3 characteristics of color

Brightness

If we see an object, it is thanks to the light which leaves from this object and reaches our eye. Without light, we see nothing. This light can be emitted by the object itself (this is the case of the filament of a bulb, the sun and the stars for example), or else reflected (the moon for example is visible only because it is lit by the sun, and most of the objects that surround our daily life do not emit light either, but we see them thanks to the light they reflect).

A light color has a greater brightness than a dark color. The brightness of a color therefore corresponds to the amount of white light reflected by that color. If all the white light is reflected, the object will be white, whereas if it does not reflect any light, it will be black. The difficulty in appreciating the luminosity of a color is to manage to disregard its saturation and its hue. Biologically, within our eye, the cells that are specialized in the perception of light are called rods.

Hue

The hue is governed by the dominant wavelength of the light received by our eye (therefore emitted or reflected by an object that we see). This wavelength is part of the visible spectrum (otherwise we just wouldn't see the object in question!).

It is the hue that allows us to distinguish a blue from a pink or a green. In our eye, cells called cones process this data. The cones of the human eye are more sensitive to wavelengths between green and yellow than to those at the end of the visible spectrum. Thus, the human eye discerns rather badly variations in color between blue and purple for example.

We call pure tint a tint that corresponds to only one wavelength. On the chromatic circle, we find these colors at the end of the circle. We then speak of saturated colors.