Chap 4 Color image processing Chapter 6 Color

Chap 4 Color image processing

Chapter 6 Color Image Processing • Two major areas: full color and pseudo color 6. 1 Color fundamentals • Primary color of light: R, G, B • Secondary color of light: magenta, cyan and yellow • Pigment or colorant-subtract or absorbs a primary color of light and reflect or transmit the other two • HIS model • Chromaticity include hue and saturation §Hue: dominant color as perceived by a observer §Saturation: the relative purity or the amount of white light §mixed with a hue

Chapter 6 Color Image Processing

• Brightness: embody the chromatic notion of intensity • Three basic properties used to describe the quality of chromatic light source: source, radiance, and brightness § Tri-stimulus values: X, Y and Z § Tri-chromatic coefficients: • CIE chromaticity diagram • • Shows color as a function of x (red) and y(green) useful for color mixing Boundary : fully saturated Equal energy point 6. 2 Color models • Purpose: facilitate the specification of colors in some standard • A specification of a coordinate system and a subspace within that system where each color is represented a single point • Two applied directions for color models: hardware and applications (color graphics)

§ § RGB models--color monitors CMY (CMYK)--color printing YIQ--color television HIS--humans describe and interpret color • The RGB Color model § Have a depth of 24 bits • The CMY color model • The YIQ model • The HIS color model • Brightness-- is a subjective descriptor that is practically impossible to measure • Ideal tool for developing image processing algorithm

• Converting colors from RGB to HIS – – Converting colors from HIS to RGB Procedures multiply H by 360 o; (1) When H is in RG sector, the RGB components are given by

– (2) GB sector – (3) BR sector • Manipulating HIS component images – Change the individual color of any region in the RGB image • 6. 3 Pseudo image processing – Assign colors to gray values based on a specification criterion – Assign colors to monochrome images from the process associated with true color images

Chapter 6 Color Image Processing

Chapter 6 Color Image Processing

Chapter 6 Color Image Processing