Light is an electromagnetic radiation that is characterized by wavelength. Wavelength is measured in nanometers. The spectrum of electromagnetic radiation is practically infinite, but the eye perceives only a part of this spectrum.

Part perceived by the human eye is called visible spectrum and contains wavelengths between 400 and 700 nm. Radiation with wavelengths below 400nm are ultraviolet rays and radio waves. Ultraviolet waves impressive photographic film. For example light from the sea or mountains give overexposure of photographic film. Radiation with wavelengths greater than 700nm is infrared radiation, X-rays and gamma.

In the visible spectrum, light rays of different wavelengths are perceived as different colors as follows:

- Purple and blue: 400-500 nm
- Green and Yellow: 500-600 nm
- Orange and red: 600-700 nm

Light emission is achieved by almost equal proportions of all the visible spectrum radiation. It also can be obtained by mixing equal proportions of the additive in the three secondary colors: red, green, blue (RGB mode).

The predominant color characteristics:

- Hue is the wavelength of radiation;

- Saturation indicate to what extent is contained radiation wavelength equivalent of a date or a shade of gray color and the same brightness.

- Brightness: The ability of color to reflect a ray with the same wavelength. Brightness gives us information about diluting a mixture of colors with white or black.