Chap 4 Color image processing

Chapter 6 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 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 24bits 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 Chapter 6 Color Image Processing

Chapter 6 Color Image Processing Chapter 6 Color Image Processing