Chapter 4. Color Image Processing 1. Color Fundamentals 2. Color Models 3. Basics of Full-Color Image Processing 4. Color Transformations 5. Color Image Smoothing and Sharpening Rafael C. Gonzalez, Richard E. Woods, “Digital image processing,” Pearson (2018). 2 1. Color Fundamentals ❖Color spectrum Color spectrum seen by passing white light through a prism. Rafael C. Gonzalez, Richard E. Woods, “Digital image processing,” Pearson (2018). 3 1. Color Fundamentals ❖Wavelengths Wavelengths comprising the visible range of the electromagnetic spectrum. Rafael C. Gonzalez, Richard E. Woods, “Digital image processing,” Pearson (2018). 4 1. Color Fundamentals ❖The absorption of light by the red, green, and blue cones in the eye Absorption of light by the red, green, and blue cones in the human eye as a function of wavelength. Rafael C. Gonzalez, Richard E. Woods, “Digital image processing,” Pearson (2018). 5 1. Color Fundamentals ❖Primary and secondary colors of light and pigments. Rafael C. Gonzalez, Richard E. Woods, “Digital image processing,” Pearson (2018). 6 1. Color Fundamentals ❖Hue, Saturation, and Brightness ➢ The characteristics generally used to distinguish one color from another are brightness, hue, and saturation. ➢ Brightness embodies the achromatic notion of intensity. ➢ Hue is an attribute associated with the dominant wavelength in a mixture of light waves. Hue represents dominant color as perceived by an observer. ➢ Saturation refers to the relative purity or the amount of white light mixed with a hue. The pure spectrum colors are fully saturated. ➢ Hue and saturation taken together are called chromaticity. → a color may be characterized by its brightness and chromaticity Rafael C. Gonzalez, Richard E. Woods, “Digital image processing,” Pearson (2018). 7 1. Color Fundamentals ❖Hue, Saturation, and Brightness ➢ The amounts of red, green, and blue needed to form any particular color are called the tristimulus values, and are denoted, X,