Upcoming Deadlines
Please take a
clicker and a
spectroscope
Homework #13 – Creating Stereoscopic 3D Images
Due Thursday, December 8th (Next week)
20 points (10 points if late)
Final Exam - Thursday, December 15th
9:45AM-12:00 Noon in this room.
For full schedule, visit course website:
ArtPhysics123.pbworks.com
Final Exam
Final Exam will have 10 short essay
questions on material covered in lecture.
Final exam counts for 50 points.
See course website for copy of last
semester’s final exam.
You may bring one page of notes doublesided (or two pages single-sided) to the
exam.
Final Exam
Sample Questions:
* What is “drag” in animation? Give an example
to illustrate your definition. What physics
principle causes “drag” to occur?
* Explain the difference between reflection and
refraction. Also give two examples of each.
Final Exam is on:
Thursday, December 15th
9:45-Noon in this room
Homework #13
Creating stereoscopic 3D images.
For this assignment you will create at least three
different stereoscopic images from photographs.
At least one of the images should have you appearing in
the photo and at least one of the images should be of a
recognizable location on campus.
You will be graded on the composition so plan your
scenes to make them interesting (especially for 3D).
Stereo 3D Photos with PhotoShop
Steps for creating stereo 3D photos in PhotoShop:
1) Snap a photo, move 3 inches to the right, take a
second photo. Avoid having objects closer than a
yard away from the camera and no moving objects!
2) Open both images in PhotoShop. Hold the shift key
and drag the right eye image on to left eye image.
3) Rename the layers “Right Eye” and “Left Eye”; make
sure the Right Eye layer is on top.
4) Double click the Right Eye thumbnail to open the
Blending Window. In Advanced Blending uncheck the
Red Channel for Red/Cyan glasses (or Green Channel
for Green/Magenta glasses).
Stereo 3D Photos with PhotoShop
Uncheck
the Red
Channel
Select
Right Eye
Layer
Homework #13
Upload your photos to your blog in an entry entitled
“Creating Stereoscopic 3D Images”
Due Thur., December 8th -- 20 points (10 points if late)
Optional: You can also create a pair of stereo-ready
images in Autodesk Maya by rendering a scene for
one image, then shifting the camera position and
rendering the second image.
Bonus Points: Create a 3D animated short, either by
stop motion or in Maya. Ten bonus points for a good
animation; twenty bonus points for a great one.
Survey Question
From which of these assignments did you
learn the most:
A)
B)
C)
D)
E)
Term paper
Homeworks using Tracker
Stop-motion animation homeworks
Homeworks using Maya
Other (reverse reference, etc.)
Review Question
Which path does light
ray take after
entering the water?
A)
B)
C)
D)
Path A
Path B
Path C
Path D
D
A
B
C
Law of Refraction
C) Path C
Angle is smaller in
the denser material.
The light ray bends
but does not cross
the normal (line
perpendicular to the
surface)
Review Question
Natural lighting underwater is primarily
from overhead because sunlight cannot
enter the water at more than about a 45
degree angle.
True or
False?
Total Internal Reflection
True.
For the same reason you
can only see the sky from
underwater when looking
up at more than about a
45 degree angle.
Mirror
See sky
Seeing Color
Spectrum of Visible Light
Wavelengths & Photons
Particles of light, called photons, each have a wavelength
that determines the color we see for that photon.
Red Photon
Yellow Photon
Green Photon
Blue Photon
Visible light is roughly from
400 nanometers (blue) to
700 nanometers (red).
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 
Use Spectrometer
Newton’s Color Wheel
Prism spectrum is a
straight line, so why
did Isaac Newton
describe color using a
circular wheel?
This segment is added to join
the two ends of the spectrum
Additive Color Wheel
There
are No
Photons
of These
Colors
R
M
Y
B
G
C
Spectral
Colors
Red
Yellow
Green
Cyan
Blue
Magenta
Adding Color Lights
Stream of red &
green photons
looks same as
yellow photons
(metamerism)
or
Theatrical lighting
Eye to
Brain
Notice overlap of red, green, &
blue is seen as white light
Simple Trichromatic Theory
Imagine that
inside your eye
are these three
guys, who send
messages to
your brain.
Yellow &
Red
photons
excite me
Yellow,
Green &
Cyan
photons
excite me
Cyan &
Blue
photons
excite me
GREG
RON
BIFF
RON
GREG
BIFF
Trichromatic: Seeing Yellow
Yellow &
Red
photons
excite me.
I’M
EXCITED
Yellow, Green &
Cyan photons
excite me.
I’M EXCITED
Cyan & Blue
photons
excite me.
Yawn.
OR
Yellow seen when
Ron and Greg are
excited, either by
yellow photons or
red & green photons.
GREG
RON
BIFF
Seeing Yellow
Sodium lamps emit near
pure yellow photons
“Electric pickle” is
also a sodium light
Color monitor can only emit red, green,
and blue (RGB); creates other colors by
selectively turning RGB pixels on or off.
Use Spectrometer
Use Spectrometer
Use Spectrometer
The Ear vs. The Eye
How the ear senses sound waves is distinct
from how the eye senses light waves.
E
A
D
Hearing an E and a D
together does not
sound like an A.
Seeing green and red
together does look like
yellow light.
Trichromatic: Seeing Magenta
Yellow &
Red
photons
excite me.
I’M
EXCITED
Yellow, Green &
Cyan photons
excite me.
Yawn.
Magenta is seen by eye
when Ron and Biff are
excited, which no single
type of photon can
GREG
achieve.
RON
BIFF
Cyan & Blue
photons
excite me.
I’M EXCITED
Maxwell Color Disk
Disk painted half red, half blue looks
magenta when rapidly spinning.
Use Spectrometer
Use Spectrometer
Use Spectrometer
Trichromatic: Two is Not Enough
With only two
receptors
Green and
Magenta look
the same.
OR
Blue & Green
photons excite me.
I’M EXCITED
Green & Red
photons excite me.
I’M EXCITED
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
Trichromatic: Seeing White
Yellow &
Red
photons
excite me.
I’M
EXCITED
Yellow, Green &
Cyan photons
excite me.
I’M EXCITED
White seen when all
three are very excited;
Gray seen when all
three less excited
Cyan & Blue
photons
excite me.
I’M EXCITED
Maxwell Color Disk
Disk with blue, green, and red filters looks
grayish white when rapidly spinning.
Use Spectrometer
Use Spectrometer
Use Spectrometer
Use Spectrometer
Value (Brightness)
The level of
excitement
indicates the
value of a
color, which is
sometimes
called the
brightness.
I’m a little
excited
Yawn.
Yawn.
Dim
Red
Light
I’M VERY
EXCITED!
Yawn.
Yawn.
Bright
Red
Light
Saturation
When white
light is mixed
in with a pure
color the eye
sees the sum
as being less
saturated.
Saturation also
called chroma.
I’M VERY
EXCITED!
Yawn.
Yawn.
Saturated
Color
Pure
Red
Light
I’m a little
excited
I’m a little
excited
I’M VERY
EXCITED!
Unsaturated
Color
Pink
Light
Hue, Saturation, Value
Color wheel is not
a single wheel but
stack of wheels
that range in
value.
Saturation
Hue
Value
Photoshop Color Picker
Value
Saturation
Hue
Saturation & Value
As lighting conditions change, value and
saturation usually vary together.
High Value and
Low Saturation
Value
Value
Saturation
Low Value and
High Saturation
Saturation
Trichromatic: Color Blindness
Red , Yellow,
Green &
Cyan photons
excite me.
I’M EXCITED
Color blindness occurs
if the eye is missing
one of the three
receptors. The other
receptors try to
compensate but cannot
distinguish some colors.
Cyan & Blue
photons
excite me.
Yawn.
Do I see red or green?
OR
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.
29 or 70?
21 or 74?
Incidence (%)
Classification
Males
Females
Anomalous
Trichromacy
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
Color and Value
Henri Matisse, Woman With Hat, 1904-5
Color and Value
Which of these two versions looks better to you? (SQUINT)
Color and Value
Color and Value
Trichromatic: After-Image
I’M
EXCITED!
Yawn.
Yawn.
First stare
at RED
I’M
EXCITED!
Would be
excited,
but tired.
I’M
EXCITED!
Then stare
at WHITE
Trichromatic
theory also
explains seeing
after-images.
Only Greg and Biff
are excited; what
color is seen?
A) Yellow
B) Magenta
C) Cyan
D) Orange
Trichromatic: After-Image
I’M
EXCITED!
Yawn.
Yawn.
First stare
at RED
I’M
EXCITED!
Would be
excited,
but tired.
I’M
EXCITED!
Trichromatic
theory also
explains seeing
after-images.
Only Greg and Biff
are excited; what
color is seen?
A) Yellow
B) Magenta
Then stare
at WHITE
C) Cyan
D) Orange
Negative After-image
Stare, unfocused, at the red cross for 10 seconds then look at white wall
Negative After-image
Cyan
Negative After-image
Stare, unfocused, at the flag for 10 seconds then look at white wall
Negative After-image
Cyan
Magenta
Yellow
Negative After-image
X
From Practical Light and Color
Negative After-image
Trichromatic: Opponency
Yellow &
Red
photons
excite me.
I’M EXCITED
Yellow, Green &
Cyan photons
excite me.
I’M EXCITED
Oh, Shut
The F*@%
Up!
Shine Red
& Green
photons
(or Yellow
photons)
Yellow seen when Greg and Roy are excited,
which can annoy Biff, who then opposes them.
Simultaneous Contrast
The green circles are identical in
hue, saturation, and value. That is,
they’re exactly the same color.
The bright yellow background
makes the green circle look
slightly darker and bluer.
The dark cyan background
makes the green circle look
slightly lighter and yellower.
Simultaneous Contrast
The green circles are identical in
hue, saturation, and value. That is,
they’re exactly the same color.
The bright yellow background
makes the green circle look
slightly darker and bluer.
The dark cyan background
makes the green circle look
slightly lighter and yellower.
Color Vision in the Eye
Three types of cones (color)
One type of rod (B/W only)
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.
Maxwell’s Color Triangle
J.C. Maxwell
formulated the
trichromatic
theory for
colors in terms
of a color
triangle.
But this
construction is
not accurate.
Eye is not a perfect
optical instrument.
Color “wheel” is
actually distorted
cone shape.
Greg %
CIE Hue-Saturation Diagram
50% Ron
50% Greg
0% Biff
Rim is full saturation,
center is white
33% Ron
33% Greg
33% Biff
Ron %
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
created using just
three spectral
wavelengths.
Why is Orange Special?
Peak sensitivities of green and red cone
are close together, so we easily separate
colors in this range. The human eye
evolved this way to spot ripe fruit and …
La Victoria Hot Sauce
Next Lecture
3D stereoscopic
imaging
Please return the spectrometers & clickers!