Color SpacesCNM 190, Spring 2010

Jeremy Huddleston & Dan Garcia

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Terms (1)

Chromaticity

Hue, “base color”

Saturation, “tint”

Brightness, Luminance, Value, “shade”

Complimentary -- add to white

Gamut -- encodable subset

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Spectral Analysis

image ref: http://thefiberopticstore.com/purchase/LED/specs/index.htm 3

CIE XYZ (1)

Commission Internationale de l’Eclairage (1931)

2D slice with Luminance = 1

Border consists of the spectral primaries

image ref: http://en.wikipedia.org/wiki/CIE_1931_color_space4

CIE XYZ (2)

Gamut for 3 primaries (R,G,B) is their triangle

Other colors would require “subtraction”

Color = rR + gG + bB

image ref: http://en.wikipedia.org/wiki/CIE_1931_color_space5

CIE XYZ (3)Choose 3 imaginary primaries (X, Y, Z)

Full Gamut

C = XX + YY + ZZ

L = X + Y + Z

x = X / Ly = Y / Lz = Z / Lx + y + z = 1

image ref: http://en.wikipedia.org/wiki/CIE_1931_color_space

X=Cr , Y=Cg, Z=Cb

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CIE XYZ (4)

Anorher Typical Encoding: CIE xyY

X = xY / y

Y = Y

Z = zY / yZ = (1 - x - y)Y / y

image ref: http://en.wikipedia.org/wiki/CIE_1931_color_space

X=Cr , Y=Cg, Z=Cb

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CIE XYZ (5)

ref: SIGGRAPH ET 2005, http://www.youtube.com/watch?v=x0-qoXOCOow8

sRGB (1)

Color = rR + gG + bB

White point = D65

“White Balance” is a linear transformation called the Von Kries transform

image ref: http://en.wikipedia.org/wiki/SRGB9

sRGB (2)

Primary Colors: RGB

Secondary Colors: CMY

Complimentary Colors: RC GM BY

image ref: http://en.wikipedia.org/wiki/SRGB10

HSV, HSL (1)

Hue: “base color”

Saturation: “purity”

Value: Luminance

image ref: Apple Keynote Screenshot, http://en.wikipedia.org/wiki/HSL_and_HSV

HSV Slice: V=1HSV Cone

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HSV, HSL (2)

Hue: “base color”

Saturation: “purity”

Lightness

image ref: http://en.wikipedia.org/wiki/HSL_and_HSV

HSL Bicone

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HSV, HSL (3)

image ref: http://en.wikipedia.org/wiki/HSL_and_HSV13

Terms (2)

Additive Color Space (light)

Subtractive Color Space (pigments)

Tone

Shade -- adding black -- “value”

Tint -- adding white -- “saturation”

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CMYK (1)

Subtractive

Primary Colors: CMY

Secondary Colors: RGB

Why do we need K?

image ref: http://en.wikipedia.org/wiki/CMYK15

CMYK (2)

image ref: http://en.wikipedia.org/wiki/CMYK

Black slightly increases our gamut

Black saves us $$$ (one ink pass rather than 3)

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Review

Spectral Graphs

CIE XYZ

HSV

HSL

sRGB

CMYK

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ExtrasHomework

BSpace

Colored Frames on Monday

Still looking for a reader

Color Combination Aesthetics

http://kuler.adobe.com

http://www.worqx.com/color/combinations.htm

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