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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?