Upcoming%20Deadlines

1
Upcoming Deadlines
For best viewing of demos, sit near the projector
screen.

• Homework 12 (Lighting a scene in Maya)
• Monday, December 7th (Last day of class)
• Final Exam
• Wednesday, December 9th from 15001700
• or
• Wednesday, December 16th from 12151430
• For full schedule, visit course website
• ArtPhysics123.pbworks.com

2
Last Homework Assignment
Light the scene created in your previous homework
assignment using one, two, and three-point
lighting.
One-point Lighting Light the scene with a single
bright spot light on the left side this is your
key light.
Created by Candace Downey
3
Last Homework Assignment
Two-point Lighting Add a dim fill light on the
right side to soften the shadows created by the
key light. Three-point Lighting Add a bright
rim light behind the letters to accentuate their
edges from the dark background.
Created by Candace Downey
4
Last Homework Assignment
Render the three scenes, save each image, and
upload them to your blog. Due by 8am on Monday,
December 7th 20 points (if late, 10) All
Assignments and Extra Credit must be turned in by
5pm on Wednesday, December 16th
Created by Candace Downey
5
Final Exam
Final Exam will have of 10 short essay questions
on material covered in lecture. Final exam counts
for 50 points. Sample Questions What is the
difference between stride and gait? How do they
affect the walking speed? Describe how a scene
would be lit using three point lighting.
6
Final Exam
Final exam is scheduled for Wednesday, December
16th In this room from 12151430 You may take
the final early on Wednesday, December 9th In
this room from 15001700
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Special Campus Event

• Animation Show of Shows
• December 7th
• (Monday)
• At 730 PM
• Morris Dailey
• Auditorium
• in Tower Hall
• FREE

8
Wanted 3D Glasses
If you have any extra 3D glasses youre willing
to donate, please bring them in. Both anaglyph
(red/blue) and polarized (Real3D) are needed.
9
Seeing Color
10
Spectrum of Visible Light
11
Wavelengths Photons
Particles of light, called photons, each have a
wavelength that determines the color we see for
that photon.
Yellow Photon
Green Photon
Blue Photon
Visible light is roughly from400 nanometers
(blue) to 700 nanometers (red).
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Demo Spectrometer
Spectrometer separates the wavelengths of light,
creating a rainbow that shows you the intensity
in each hue (color).
Light bulb Spectrum
? Long Wavelength
Short ?
13
Use Spectrometer
14
Newtons Color Wheel
Prism spectrum is a straight line, so why did
Isaac Newton describe color using a circular
wheel?
15
Additive Color Wheel
R
Y
M
Red Yellow Green Cyan Blue Magenta
G
B
C
16
Adding Color Lights
Stream of red green photons looks same as
yellow photons (metamerism)
YELLOW
Eye to Brain
or
Notice overlap of red, green, blue is seen as
white light
Theatrical lighting
17
Simple Trichromatic Theory
Yellow Red photons excite me
Yellow, Green Cyan photons excite me
Imagine that inside your eye are these three
guys, who send messages to your brain.
Cyan Blue photons excite me
GREG
RON
BIFF
BIFF
RON
GREG
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Trichromatic Seeing Yellow
Yellow, Green Cyan photons excite me. IM
EXCITED
Cyan Blue photons excite me. Yawn.
Yellow Red photons excite me. IM EXCITED
OR
Yellow seen when Ron and Greg are excited, either
by yellow photons or red green photons.
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Seeing Yellow
Sodium lamps emit pure yellow photons
Color monitor can only emit red, green, and blue
(RGB) creates other colors by selectively
turning RGB pixels on or off.
Electric pickle is also a sodium light
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Use Spectrometer
21
Use Spectrometer
22
Use Spectrometer
23
The Ear vs. The Eye
How the ear senses sound waves is distinct from
how the eye senses light waves.
E
D
A
Hearing an E and a D together does not sound like
an A.
Seeing green and red together does look like
yellow light.
24
Trichromatic Seeing Magenta
Cyan Blue photons excite me. IM EXCITED
Yellow, Green Cyan photons excite me. Yawn.
Yellow Red photons excite me. IM EXCITED
Magenta is seen by eye when Ron and Biff are
excited, which no single type of photon can
achieve.
25
Maxwell Color Disk

• Disk painted half red, half blue looks magenta
  when rapidly spinning.

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Use Spectrometer
27
Use Spectrometer
28
Use Spectrometer
29
Trichromatic Two is Not Enough
With only two receptors Green and Magenta look
the same.
Blue Green photons excite me. IM EXCITED
Green Red photons excite me. IM EXCITED
OR
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Mixing Blue Red Paint

• Mixing paint or ink is different from adding
  colors together by light.

Mix of blue and red paint produces a blackish
brown
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Trichromatic Seeing White
Cyan Blue photons excite me. IM EXCITED
Yellow, Green Cyan photons excite me. IM
EXCITED
Yellow Red photons excite me. IM EXCITED
White seen when all three are very excited Gray
seen when all three less excited
32
Maxwell Color Disk
Disk with blue, green, and red filters looks
grayish white when rapidly spinning.
33
Use Spectrometer
34
Use Spectrometer
35
Use Spectrometer
36
Use Spectrometer
37
Value (Brightness)
Yawn.
The level of excitement indicates the value of a
color, which is sometimes called the brightness.
Yawn.
Im a little excited
Dim Red Light
Yawn.
Yawn.
IM VERY EXCITED!
Bright Red Light
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Saturation
IM VERY EXCITED!
When white light is mixed in with a pure color
the eye sees the sum as being less saturated.
Saturation also called chroma.
Yawn.
Yawn.
Pure Red Light
Im a little excited
Im a little excited
IM VERY EXCITED!
Pink Light
39
Hue, Saturation, Value
Color wheel is not a single wheel but stack of
wheels that range in value.
Saturation
Hue
Value
40
Photoshop Color Picker
Value
Saturation
Hue
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Saturation Value
As lighting conditions change, value and
saturation usually vary together.
High Value andLow Saturation
Low Value andHigh Saturation
Value
Saturation
42
Trichromatic Color Blindness
Red , Yellow, Green Cyan photons excite me. IM
EXCITED
Cyan Blue photons excite me. Yawn.
OR
Color blindness occurs if the eye is missing one
of the three receptors. The other receptors try
to compensate but cannot distinguish some colors.
Do I see red or green?
43
Color Blindness
Weakness or absence of one of the three types of
cones is the cause of color blindness, leading to
a reduced ability to distinguish colors.
Classification Incidence () Incidence ()
Classification Males Females
AnomalousTrichromacy 6.3 0.37
Protanomaly(Red-cone weak) 1.3 0.02
Deuteranomaly(Green-cone weak) 5.0 0.35
Tritanomaly(Blue-cone weak) 0.0001 0.0001
Dichromacy 2.4 0.03
Protanopia(Red-cone absent) 1.3 0.02
Deuteranopia(Green-cone absent) 1.2 0.01
Tritanopia(Blue-cone absent) 0.001 0.03
Rod Monochromacy(no cones) 0.00001 0.00001
29 or 70?
21 or 74?
44
Color and Value
Henri Matisse, Woman With Hat, 1904-5
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Color and Value
Which of these two versions looks better to you?
(SQUINT)
46
Color and Value
47
Color and Value
48
Trichromatic After-Image
Trichromatic theory also explains seeing
after-images.
Yawn.
Yawn.
IM EXCITED!
First stare at RED
Only Greg and Biff are excited what color is
seen?
IM EXCITED!
IM EXCITED!

• Yellow
• Magenta
• C) Cyan
• D) Orange

Would be excited, but tired.
Then stare at WHITE
49
Trichromatic After-Image
Trichromatic theory also explains seeing
after-images.
Yawn.
Yawn.
IM EXCITED!
First stare at RED
Only Greg and Biff are excited what color is
seen?
IM EXCITED!
IM EXCITED!

• Yellow
• Magenta
• C) Cyan
• D) Orange

Would be excited, but tired.
Then stare at WHITE
50
Negative After-image
Stare, unfocused, at the red cross for 10 seconds
then look at white wall
51
Negative After-image
Cyan
52
Negative After-image
Stare, unfocused, at the flag for 10 seconds then
look at white wall
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Negative After-image
Yellow
Cyan
Magenta
54
Negative After-image
X
From Practical Light and Color
55
Negative After-image
56
Color Vision in the Eye
Three types of cones (color) One type of rod (B/W
only)
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Human Color Vision
The human eye is not a perfect optical instrument
so attempts to create color systems with
geometrically perfect wheels or triangles are
misguided.
58
Maxwells Color Triangle
J.C. Maxwell formulated the trichromatic theory
for colors in terms of a color triangle. But
this construction is not accurate.
59
CIE Hue-Saturation Diagram
Eye is not a perfect optical instrument. Color
wheel is actually distorted cone shape. Rim is
full saturation, center is white
Greg
50 Ron 50 Greg 0 Biff
33 Ron 33 Greg 33 Biff
Ron
60
Gamut of Color
Outer horseshoe shape is the gamut of colors
which the human eye can distinguish. Inner
triangle is the gamut of colors that may be mixed
using just three spectral wavelengths.
61
Why is Orange Special?
Red
Green
CIE color wheel
Blue
Cone Sensitivity
Wavelength
Peak sensitivities of green and red cone are
close together, so we easily separate colors in
this range, probably to spot ripe fruit and
La Victoria Hot Sauce
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Next LectureMaking Color

• No Homework for this WednesdayHomework 12 due
  Monday, Dec. 7th

Please return the spectrometers clickers!