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

Chap 4 Color image Chap 4 Color image processingprocessing

Chap 4 Color image Chap 4 Color image processingprocessing

Chapter 6Color Image Processing


•Two major areas: full color and pseudo color6.1 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 saturationHue: dominant color as perceived by a observerSaturation:the relative purity or the amount of white light mixed with a hue



• Brightness: embody the chromatic notion of intensity

• Three basic properties used to describe the quality of chromatic light source: source, radiance, and bright

ness 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 som

e standard• A specification of a coordinate system and a subspa

ce within that system where each color is represented a single point

• Two applied directions for color models: hardware and applications (color graphics)

ZYX

ZZ

ZYX

Yy

ZYX

Xx

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

B

G

R

Y

M

C

1

1

1

311.0523.0212.0

321.0275.0596.0

114.0587.0299.0

Q

I

Y

• Converting colors from RGB to HIS

– Converting colors from HIS to RGB– Procedures– multiply H by 360o; – (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







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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