Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces...
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Transcript of Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces...
![Page 1: Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces –RGB, CMY, YIQ, HLS, CIE –CIE XYZ, CIE xyY and CIE.](https://reader036.fdocuments.us/reader036/viewer/2022062309/56649ec95503460f94bd6398/html5/thumbnails/1.jpg)
Color
![Page 2: Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces –RGB, CMY, YIQ, HLS, CIE –CIE XYZ, CIE xyY and CIE.](https://reader036.fdocuments.us/reader036/viewer/2022062309/56649ec95503460f94bd6398/html5/thumbnails/2.jpg)
Contents
• Light and color
• The visible light spectrum
• Primary and secondary colors
• Color spaces– RGB, CMY, YIQ, HLS, CIE– CIE XYZ, CIE xyY and CIE diagram
properties
![Page 3: Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces –RGB, CMY, YIQ, HLS, CIE –CIE XYZ, CIE xyY and CIE.](https://reader036.fdocuments.us/reader036/viewer/2022062309/56649ec95503460f94bd6398/html5/thumbnails/3.jpg)
What do we see?
• Visible electromagnetic radiation• The type of electromagnetic wave that is
visible to the human eye.• Electromagnetic radiation that has a
wavelength in the range from about 4,000 (violet) to about 7,700 (red) angstroms and may be perceived by the normal unaided human eye.
http://www.answers.com/color
![Page 4: Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces –RGB, CMY, YIQ, HLS, CIE –CIE XYZ, CIE xyY and CIE.](https://reader036.fdocuments.us/reader036/viewer/2022062309/56649ec95503460f94bd6398/html5/thumbnails/4.jpg)
Electromagnetic radiation
• Electromagnetic radiation is a kind of energy radiated in the form of a wave
• The frequency define the energy– E = h – And the hue: = c
![Page 5: Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces –RGB, CMY, YIQ, HLS, CIE –CIE XYZ, CIE xyY and CIE.](https://reader036.fdocuments.us/reader036/viewer/2022062309/56649ec95503460f94bd6398/html5/thumbnails/5.jpg)
Electromagnetic spectrum and the visible light spectrum
![Page 6: Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces –RGB, CMY, YIQ, HLS, CIE –CIE XYZ, CIE xyY and CIE.](https://reader036.fdocuments.us/reader036/viewer/2022062309/56649ec95503460f94bd6398/html5/thumbnails/6.jpg)
What is color?
• It is a sensation• “Color is actually light waves that hit our eyes,
translated into nerve impulses, and interpreted by our brains as all the various colors around us.”
• Three components: RGB• Cones
– Reds (low frequency)– Greens (medium frequency)– Blues (high frequency)
http://www.stlukeseye.com/images/illustrations/anatomy_globe.jpg
![Page 7: Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces –RGB, CMY, YIQ, HLS, CIE –CIE XYZ, CIE xyY and CIE.](https://reader036.fdocuments.us/reader036/viewer/2022062309/56649ec95503460f94bd6398/html5/thumbnails/7.jpg)
Mixing colors
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Primary and secondary colors
Additive Colors
Subtractive Colors
![Page 9: Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces –RGB, CMY, YIQ, HLS, CIE –CIE XYZ, CIE xyY and CIE.](https://reader036.fdocuments.us/reader036/viewer/2022062309/56649ec95503460f94bd6398/html5/thumbnails/9.jpg)
![Page 10: Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces –RGB, CMY, YIQ, HLS, CIE –CIE XYZ, CIE xyY and CIE.](https://reader036.fdocuments.us/reader036/viewer/2022062309/56649ec95503460f94bd6398/html5/thumbnails/10.jpg)
Color spaces
• Systems to define colors numerically• Device oriented
– RGB– CMY– YIQ
• Human oriented– HSV– CIE
![Page 11: Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces –RGB, CMY, YIQ, HLS, CIE –CIE XYZ, CIE xyY and CIE.](https://reader036.fdocuments.us/reader036/viewer/2022062309/56649ec95503460f94bd6398/html5/thumbnails/11.jpg)
(1, 1, 0) Yellow
(0, 1, 0) Green
(1, 0, 0) Red
(1, 0, 1)Magenta
(0, 0, 1) Blue (0, 1, 1) Cyan
(1, 1, 1)White
(0, 0, 0)Black
RGB
• Additive model– Intensity of the three
components
![Page 12: Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces –RGB, CMY, YIQ, HLS, CIE –CIE XYZ, CIE xyY and CIE.](https://reader036.fdocuments.us/reader036/viewer/2022062309/56649ec95503460f94bd6398/html5/thumbnails/12.jpg)
RGB
• Features– It is used by hardware devices
• True color: 2563 = 16.777.216
– It is a standard on computing• bgcolor="#FFFFFF”
• Problems– Their variations are not lineal– It isn’t intuitive
![Page 13: Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces –RGB, CMY, YIQ, HLS, CIE –CIE XYZ, CIE xyY and CIE.](https://reader036.fdocuments.us/reader036/viewer/2022062309/56649ec95503460f94bd6398/html5/thumbnails/13.jpg)
(1, 1, 0) Blue
(0, 1, 0) Magenta
(1, 0, 0) Cyan
(0, 0, 1) Yellow (0, 1, 1) Red
(1, 1, 1)Black
(0, 0, 0)White
(1, 0, 1)Green
CMY
• Subtractive model
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CMY
• Complementary of RGB[CMY] = [1,1,1] - [RGB]
• Used in printing
• Use of CMYK– Black (K) is added
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HSV
• Projection of RGB diagram about the biggest diagonal
• Polar coordinates– Hue
– Saturation
– Value or brightness
• Transformation to RGB (no lineal)
0 Red
S
H
V60 Yellow120 Green
180Cyan
240 Blue 300 Magenta
0.0 Black
1.0 White
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HLS
• Two cones joined, with white on the upper vertex
• Variation of HSV– L: lightness
SH
L
60 Yellow120 Green180Cyan
240 Blue 300 Magenta
0.0 Black
1.0 White
0 Red
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YIQ
• Lineal transformation of RGB
• Used by the NTSC (National Television Standards Committee)
• Y is brightness (used in black-and-white television monitors)
B
G
R
Q
I
Y
311.0523.0212.0
321.0275.0596.0
144.0587.0299.0
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CIE Diagram
http://www.lumitroncorp.com/rsrcs/CIE.gif
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CIE
• 1931: measurement of color by the CIE (Commission International de L'Eclairage)
• Based on Tristimulus Vision Theory
• Represents any color detected by the human being
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Definition of CIE diagram
• Experimentally– Red (700 nm)– Green (546,1 nm)– Blue (435,8 nm)
• There is negative values (added the primary to the sample)– They can’t be used– It is made adding the primary to the
sample
http://www.imel1.kuis.kyoto-u.ac.jp/education/dip-arch/pre/images/graph10.gif
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The three standard primaries of CIE
• They are not real colors
• The functions are defined in tabular form (at 1 nm interval)
• They are standards to define colors
http://www.imel1.kuis.kyoto-u.ac.jp/education/dip-arch/pre/images/xyz.gif
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CIE XYZ
• One color is defined by the X, Y, Z components.
• The projection on the XY plane produces the CIE Chromatic Diagram.
X
Y
Z
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CIE xyY
• Normalizing the values:x + y + z = 1
• Y is the luminance information
– function y() was chosen in this way
http://hypertextbook.com/physics/waves/color/chromaticity.jpg
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Properties of CIE diagram
• Gamut of different devices
• The periphery is the spectrum colors
• The purple line are non-spectral colors
• The spectral component of a color is calculated with the line to the center
http://www.tu-harburg.de/rzt/tuinfo/periph/drucker/Color_Reproduktion/cie_spectrum.gif
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Color spaces
http://www.gg.caltech.edu/~dhl/images.html
![Page 26: Color. Contents Light and color The visible light spectrum Primary and secondary colors Color spaces –RGB, CMY, YIQ, HLS, CIE –CIE XYZ, CIE xyY and CIE.](https://reader036.fdocuments.us/reader036/viewer/2022062309/56649ec95503460f94bd6398/html5/thumbnails/26.jpg)
Cube RGB