1 vladimir botchko [email protected] lecture 5. color image processing lappeenranta university of...
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Vladimir Botchko [email protected]
Lecture 5. Color Image ProcessingLecture 5. Color Image Processing
Lappeenranta University of Technology (Finland)
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Color Image ProcessingColor Image Processing
Fundamentals Color models Pseudocolor image processing Full color image processing Color transformations Smoothing and Sharpening Color segmentation Noise in color images Color image compression Multispectral image processing
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Fundamentals
Colors in the visible range of wavelengths (upper left), mixtures of light (additive primaries) (upper right) and color bars used in analysis.
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Color models
Relative color gamuts of a dipslay and a printer in XYZ chromaticity coordinate system (right).
Left - XYZ color space.
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Color Image ProcessingColor Image Processing
Fundamentals Color models Pseudocolor image processing Full color image processing Color transformations Smoothing and Sharpening Color segmentation Noise in color images Color image compression Multispectral image processing
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Color models
RGB space. The right image is a rotated left image (for correspondence: BL is black, W is white).
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Hue, saturation, intensity system
Y aR cG dBr g b
r g bW P
W Sr g b
U
V|||
W|||
arccos[( / ) ( / ) ( / ) ]
min( , , )
/
2
6 1 3 1 3 1 3
1 3
2 2 2 1 2
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Color models
Chromaticity
r R R G B
g G R G B
b B R G B
UV|W|
/ ( )
/ ( )
/ ( )
g
r0r g b 1b r b 1
w( / , / )1 31 3
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Color Image ProcessingColor Image Processing
Fundamentals Color models Pseudocolor image processing Full color image processing Color transformations Smoothing and Sharpening Color segmentation Noise in color images Color image compression Multispectral image processing
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Pseudocoloring
Myocardial perfusion study. Left is a heart attack (blue region increased), right is normal.
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Pseudocoloring
Right – three images: elevation relief (upper left), the color coded magnetic field (higher values are yellowish) (upper right), the composition of first two. Left – underpainting revealed through color dipslay (Prof. L. MacDonald, Derby University,GB).
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Color Image ProcessingColor Image Processing
Fundamentals Color models Pseudocolor image processing Full color image processing Color transformations Smoothing and Sharpening Color segmentation Noise in color images Color image compression Multispectral image processing
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Painting Restoration. A Queen house , London. The part of painting was copied from another painting (upper right) and
used for restoration of the lost painting part.
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Color Image ProcessingColor Image Processing
Fundamentals Color models Pseudocolor image processing Full color image processing Color transformations Smoothing and Sharpening Color segmentation Noise in color images Color image compression Multispectral image processing
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Color segmentation
Image segmentation based on color feature: burnt forest area, forest fire, dead forest (brown).
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Color Image ProcessingColor Image Processing
Fundamentals Color models Pseudocolor image processing Full color image processing Color transformations Smoothing and Sharpening Color segmentation Noise in color images Color image compression Multispectral image processing
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Color image compression.
Original color image (upper left), compressed image (upper right), error histogram in compression (the error is a delta E – the smallest color noticible difference) and error image (large error values are white).
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Color Image ProcessingColor Image Processing
Fundamentals Color models Pseudocolor image processing Full color image processing Color transformations Smoothing and Sharpening Color segmentation Noise in color images Color image compression Multispectral image processing
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Using a ratio image to enhance road detail (two upper is a multispectral image components)
The third image (lower) is the dividend of the first two
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Color analysis. The Munsell Book of Color contains a set of color patches
http://www.it.lut.fi/research/color/demonstration/demonstration.html
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Color analysis. Metameric spectra. Color is the same at one illumination (left patches) and different at another
illumination (right patches).