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Practical Image and Video Processing Using MATLAB® by Oge Marques

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Chapter 16

Color Image Processing

What Will we Learn?

  • What are the most important concepts and terms related to color perception?
  • What are the main color models used to represent and quantify color?
  • How are color images represented in MATLAB?
  • What is pseudocolor image processing and how does it differ from full-color image processing?
  • How can monochrome image processing techniques be extended to color images?

16.1 The Psychophysics of Color

Color perception is a psychophysical phenomenon that combines two main components:

1. The physical properties of light sources (usually expressed by their spectral power distribution (SPD)) and surfaces (e.g., their absorption and reflectance capabilities).

2. The physiological and psychological aspects of the human visual system (HVS).

In this section, we expand on the discussion started in Section 5.2.4 and present the main concepts involved in color perception and representation.

16.1.1 Basic Concepts

The perception of color starts with a chromatic light source, capable of emitting electromagnetic radiation with wavelengths between approximately 400 and 700 nm. Part of that radiation reflects on the surfaces of the objects in a scene and the resulting reflected light reaches the human eye, giving rise to the sensation of color. An object that reflects light almost equally in all wavelengths within the visible spectrum is perceived as white, whereas an object that absorbs most of the incoming light, regardless of the wavelength, is seen ...

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