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Chapter 6 Color Image Processing. Color fundamentals. 六個區域 : 紫 , 藍 , 綠 , 黃 , 橙 , 紅 每個顏色都是平順的融入下一種顏色中. Chapter 6 Color Image Processing. 彩色光頻譜範圍 400~700nm. 描述彩色光源品質的三種基本量 輻射度 (Radiance) The total amount of energy that flows from the light source Measured in watts (W) - PowerPoint PPT Presentation
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Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
六個區域 : 紫 , 藍 , 綠 , 黃 , 橙 , 紅每個顏色都是平順的融入下一種顏色中
Color fundamentals
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
描述彩色光源品質的三種基本量• 輻射度 (Radiance)
• The total amount of energy that flows from the light source
• Measured in watts (W)• 照度 (Luminance)
• The energy an observer perceives from a light source.• Measured in lumens (lm)
• 亮度 (Brightness)• A subjective descriptor.
彩色光頻譜範圍400~700nm
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
錐狀細胞 (Cones) 對於色彩感受度可以分為三類65% -- red33% -- green2% -- blue (but the blue cones are the most sensitive)
三 “原 (primary)” 色 (RGB) 不代表它們可以組成頻譜上各種任意的顏色,除非波長可改變
CIE designatedRed: 700 nmGreen : 546.1 nmBlue: 435.8 nm
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
加成性的原色 ( 光的三原色 )•紅、藍、綠•可見的顏色是由物體直接發出•例 : 綠色—物體發出綠光
•相減性的原色 ( 顏料的三原色 )
•紫紅、青、黃•物體吸收一種光的原色而反射另外的兩種光 .
•例 : 黃色—物體吸收藍光,反射紅及綠光
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
• 用來區分彩色的特徵– 亮度 Brightness
• 色彩強度– 色調 Hue
• 與混合光波的主要波長有關 , 代表觀察者所查覺得主要色彩– 飽和度 Saturation
• 色彩的相度純度或與白光混合的量
Chromaticity( 色度 ) – 包含 Hue 及 Saturation
Chapter 6Color Image Processing
Chapter 6Color Image Processing
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
CIE 色度圖橫軸 : 紅縱軸 : 綠Z: 1-(x+y) 藍• 所有頻譜色彩圍繞
在舌形邊界 ( 純色 )• 等能量點 : 三原色等
比例• 連接任一兩點的直線
定義兩端點顏色可以組合的所有顏色
• 由等能量點連至邊線可以定義該色頻顏色的深淺
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
色彩全域Color gamut
Color monitor
Color printing device
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
色彩模型 (Color model, color space, color system)•Cartesian coordinate system•Color is defined by vector•Normalized value in the range [0,1]
RGB 色彩模型
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
B
GR
Plane with R=128
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
2166
402162563
40 顏色保留給系統進行處理與使用,其他 (216 色 ) 共通,即所謂的安全色彩,其顯示與硬體無關
FFFFFF FFFFCC CCFFFF
FFCCFF
FF0000
安全色彩• 系統• 網路• 瀏覽器
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
21663
RGB 均只有六個值• 0,51,102,153,204,255• 下圖將 6.10 圖以立體顯示
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
• CMY 及 CMYK 色彩模型– 青 Cyan, 紫紅 magenta, 及黃 yellow 是光的次色彩– 下列公式中所有的顏色值均被正規化至 [0,1] 之間– K 為純黑色 : 避免使用 C,M,Y 混出髒的黑色
Chapter 6Color Image Processing
Chapter 6Color Image Processing
B
G
R
Y
M
C
1
1
1 塗有青色 (C) 的原料被白光照射時,紅光 (R) 被吸收 (C=1-R)
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
HSI 色彩模型•Hue, Saturation, and Intensity
RGB model – color generation( camera, monitor…)CMY model – color printingHSI model – color description, 根據人類直覺的彩色描述 發展影像處理的工具
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
• Converting colors from RGB to HSI (R,G,B are normalized )
BGRI
BGRBGR
S
BGBRGR
BRGR
with
GBif
GBifH
3
1
),,min(1
1
cos
360
212
21
1
Chapter 6Color Image Processing
Chapter 6Color Image Processing
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
• Converting colors from HSI to RGB
)(*3
)60cos(
cos1
)1(
120
)240120(sector
)(*3
)60cos(
cos1
)1(
)1200(sector
360*
GRIB
H
HSIG
SIR
H-H
HGB
BRIG
H
HSIR
SIB
HRG
HH
Chapter 6Color Image Processing
Chapter 6Color Image Processing
)(*3
)60cos(
cos1
)1(
240
)360240(sector
BGIR
H
HSIB
SIG
H-H
HBR
請注意譯本的公式有誤
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing
請注意譯本的圖片有誤
Digital Image Processing, 2nd ed.www.imageprocessingbook.com
© 2002 R. C. Gonzalez & R. E. Woods
Chapter 6Color Image Processing
Chapter 6Color Image Processing