Announcements 4/9/12
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Prayer
Roy G. Biv - http://www.youtube.com/watch?v=Gf33ueRXMzQ (2:41)
HW 26 due today (but it’s very likely Claira won’t pick it up until
Thursday night. Shhh!)
Exam 3 – Should be graded/entered by end of today
Final Exam: My apologies, can’t take it in the Testing Center.
Scheduled exam date/time: Tues Apr 17, 3-6 pm.
a. Any conflicts?
b. Start at 2 pm?
c. Some detailed info on the problems…
Foxtrot
Reading Quiz
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Just kidding
The Goal
Worked Example
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X=
Y=
Z=
Normalize (because “color” should not depend on overall intensity)
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x=
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y=
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z=
xyY
Another Worked Example
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What is (x,y) for a delta function at 560 nm?
My estimates:
X = 0.59
Y = 0.98
Z=0
x = .38
y = .62
Do that for every wavelength  the “locus” curve
Chromaticity Diagram
Things to observe
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The locus
Example: 560 nm 
(0.38, 0.62)
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The white point =
(0.33, 0.33)
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Basic color mixing
(blue + green =
cyan, etc.)
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“Line of purples”
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Linearity: more
advanced combining
colors
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Complementary
colors (can mix to
get white)
sRGB
“green” = (0.30, 0.60)
(If xyY is specified, must first transform to XYZ) “red” =
(0.65, 0.33)
“blue” = (0.15, 0.06)
sRGB
Mixing three
sources:
triangle
 “Gamut”
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“green” = (0.30, 0.60)
“red” =
(0.65, 0.33)
“blue” = (0.15, 0.06)
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On the advantages
of monochromatic
sources
“green” = (0.30, 0.60)
“red” = (0.65, 0.33)
“blue” = (0.15, 0.06)
What’s the Color of Blackbody Radiation?
The Sun
The Sun
K
Wikipedia
“Color
Temperature”
5000K
2000K
1000K
Color of the Sun?
“Stop It”
The Sun
For a given (x,y) point
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Dominant color
(hue), lD
Saturation (purity), P
What about this point?
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Complement color,
lC
Summary: Ways to Specify Color
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R,G,B (original color matching functions)
X,Y,Z
x,y,Y
hue, saturation, Y (“hue, brightness, saturation”)
sRGB R,G,B coordinates (if in sRGB gamut)
That’s All, Folks