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W2D1
W2D1
HSV colour model
Source: http://www.ncsu.edu/scivis/lessons/colormodels/color_models2.html
Primary coloursRedGreenBlue
SecondaryCyanMagentaYellow
Secondary=White-Primary(create colors for print)
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HSV colour model, tertiary colours
Add the coloursbetween primary and secondary
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HSV colour model
Colour specified by 3 parameters:-hue (angle on disc)- saturation (how dominant is the hue relative to the other colours)-value (overall intensity of the light)
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HSV colour model
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Colour = sensation. It is determined by:-Light-Physiology-Psychology
Experiment
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Read the colors of the words in col 1, then col 3, then col 2:
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http://www.michaelbach.de/ot/col_lilacChaser/index.html
Experiments with optical illusions:
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Capturing images (with digital camera…)
Charge motion
Ch
arg
e m
otio
n
Serial (horizontal) register
Parallel (vertical) registers
Pixel
Image area(exposed to light)
Output amplifier
masked area(not exposed to light)
(slides by Claudio Cumani, European Southern Observatory)
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Representing the intensity of a primary color (eg. Red)
• left: 3 bits per color (numbers 0 to 7)• right: 8 bits per color (numbers 0 to 255)
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Lossless compression• original x by y pixels• stored: the color of every pixel, row by row
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Lossless compression• original x by y pixels• stored: the color of every pixel, row by row
A lot of black pixels!(R,G,B=0,0,0)
Replace sequence of black pixels by 2 numbers:“0, n”n - nr repetitions.
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Image from a digital camera (10MB) stored as 128kB
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8x8 blocks of pixelsJPEG compression
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<- 1 block.
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We can store the average value for every block
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What if we stored the average for 4x4 blocks?