Electromagnetic Radiation and Perceived Color

Visible light constitutes a small portion of the electromagnetic spectrum. Human vision interprets differing wavelengths within this range as distinct hues. The interaction of light with a surface determines the perceived color.

The Nature of Light Absorption and Emission

Materials possess unique atomic and molecular structures. When light strikes a substance, certain wavelengths are absorbed; the absorbed energy excites electrons within the material. The remaining, unabsorbed wavelengths are either transmitted through or scattered by the material. This scattered or transmitted light reaches our eyes, defining our perception of the substance's color.

Spectral Composition and Surface Interaction

The color of an object is determined by its spectral reflectance curve – a plot of the percentage of light the object reflects across the visible spectrum. A surface that absorbs all visible wavelengths appears black. Conversely, a surface that scatters most visible wavelengths without significant absorption appears to exhibit a different quality.

The Role of Pigments and Dyes

Pigments and dyes are substances that selectively absorb certain wavelengths. In paints, textiles, and other colored materials, these compounds are responsible for the observed color. Different pigments and dyes have different absorption spectra, resulting in a wide variety of perceived colors.

Additive and Subtractive Color Mixing

• Additive Mixing: The process of combining different colors of light. The primary additive colors are red, green, and blue (RGB). When combined in equal intensities, these create the perception of "brightness."
• Subtractive Mixing: The process of combining colored substances that absorb certain wavelengths. The primary subtractive colors are cyan, magenta, and yellow (CMY). These absorb different portions of the spectrum. When combined, they absorb more wavelengths, resulting in darker colors.

Visual Perception of Surfaces

The color we perceive is influenced not only by the spectral reflectance of the surface but also by factors such as the ambient light source, surrounding colors (color constancy), and individual differences in color vision.