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Vision & Light
Vision & Perception
The whole point of any display is to deliver clear
and comprehensible information to an audience.
&
Blurry
Clear
Our Optical System
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The light passes through the cornea, a clear covering in
front of the eye.
The lens, or iris, is behind the cornea and the pupil in the
center.
The pupil is an opening in which the light passes. The iris
is what causes the diameter of the pupil change. As the
intensity of light decreases, the diameter will become larger
and allows more light through.
When the lens focuses the light at the back of the eye, it’s
called the retina.
Our Optical System
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There are two types of light receptors that cover the surface
of the retina – cones and rods.
Cones are receptors used to see under bright conditions.
They are placed at the center of the retina. Cones also let us
have the ability to sense color and see the fine details in what
we see.
Rods are very sensitive to low levels of light and do not pick
up color. Rods help us see during the night. Most rods are
located on the perimeter of the retina, which makes our
peripheral vision to be blurry and unsharp.
The optical nerve which transmit the visual data to the brain,
which are located behind the cones and rods.
Visual Field
**THE SIZE OF EACH EYE’S VISUAL FIELD IS
IMPRESSIVE: 135 HIGH AND 160 WIDE. ALL
TOGETHER, THE HORIZONTAL FIELD OF
VIEW IS 200**
Light
The two theories of light
Light, like sound is made of waves of
energy.
Light is made of small particles, called
photons.
Light waves- the waves of energy are
categorized by their wavelength.
How fast does light travel
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The speed of light = 186,000 m / s
That's miles per second! Or 700 Million
Miles per hour.
It takes 1.2 seconds for light to travel from
the Moon to the Earth and 8.5 minutes from
the Sun to the Earth.
Speed of sound = 769 miles per hour
Of interest:
Proxima Centauri is the nearest star to the
sun. If we could travel at the speed of light it
would take us 4.22 years to get there.
Gliese 581 c is thought to be the closest
habitable planet. It's only 20.4 light years
away.
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This is the Electromagnetic Spectrum. The
waves of energy are categorized by their
wavelength. We can only see a small section
of the electromagnetic spectrum, which is the
color spectrum, shown in color above.
Three Aspects of Light
Wavelength: Distinguishes the different types
of light.
Frequency: Determines the color of the light.
Amplitude: Refers to the brightness of a light
wave.
Wavelengths
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The distance in meters between two
corresponding points of two consecutive
cycles.
With light, that distance is typically
measured in nanometers. A nanometer is
equal to one billionth of a meter (10^-9 m).
The Sun’s Effects
The best explanation of
why we see light only
in wavelengths of 400750 nanometers is that
these wavelengths
are the make up of
sunlight through our
atmosphere.
Frequency
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Frequency is the number of cycles in a
given time period, measured in Hertz (Hz).
The frequency of a light wave determines
it’s color.
1Hz = 1 cycle/sec
Frequency
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Gamma Rays have a frequency of 10^18 Hz
Radio Waves have a frequency of 10^4 Hz
Frequency and Colors
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Green is at the center of the color spectrum.
Blue light waves have a higher frequency, which
makes it harder to see.
Red light waves have a lower frequency.
Visible light with a frequency of about 10^14 Hz
means that our eyes receive just more than four
hundred trillion light waves every second!
(WOW!)
Frequency and
Wavelengths
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As wavelength increases, the frequency
decreases.
Think of it this way, if there are a lot of little waves
hitting the beach quickly, they could be said to
have a short wavelength and a high frequency.
If there are only a few big waves hitting beach
slowly, they would have a long wavelength and a
lower frequency/
Waves and Cycles
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The two basic quantities which describe a
light wave are the frequency f, of the wave
(usually given in hertz, HZ, or cycles per
second), and the wavelength, . These
quantities are related to each other and to
the speed of light c, by: λƒ = c
Amplitude
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Amplitude is the magnitude of a signal.
As represented on a sine wave, it is the
intensity of a wave.
Amplitude
Higher & Lower Amplitudes of Sine waves @
Common Frequencies
Amplitude
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Amplitude of a light wave is what our eyes
perceive as brightness. The greater the amplitude
of a light wave, the further the wave is displaced
from the midline, and brighter the light.
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End Part 1
Behavior of Light
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Light speed can change depending on the
material it goes through. When light speed
changes, the behavior of light changes.
Absorption
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When trying to darken a room, use dark
materials. The reason is that light is
absorbed by dark colors, close to black.
Have you ever noticed that some outdoor
athletes, like football players, put black
streaks under their eyes?
The “eye black” absorbs the sunlight,
reducing reflections to the eyes.
Mixing Colors of Light
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You may remember playing with paints and
inks that yellow and blue make green, and
mixing all your paints usually creates black.
It’s different with light. Here’s how:
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Black is defined as the absence of light.
White is the perceived color when red, blue, and
green are present in equal proportions.
Chromaticity Diagram
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Notice that there is no black light
represented on the diagram.
“Black Light”
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IS NO SUCH THING
AS BLACK COLORED
LIGHT; BLACK IS CREATED
BY THE ABSENCE OF
LIGHT
Of Interest…
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When we see a field of green grass, our
brains see that grass as green, because
the grass absorbs the blue and red parts of
the sunlight illuminating it.
Only the proper green wavelength is
reflected back for interpretation by our eyes
and brains.
Of Interest…
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If none of the light was absorbed, it would
appear whilte. If all of the light were
absorbed, it would appear black.
If we try seeing the field at night, it would
appear gray because of our night vision is
sensitive to grayscale more than to
saturation or hue.
“Defining” Color
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Value should be thought of as a grayscale.
“Defining” Color
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Hue is the color represented.
Color Temperature
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Color temperature is a scientific
measurement for expressing the
distribution of the colors radiating from a
light source, expressed on the Kelvin
Scale.
Color Temperature
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The higher the color temperature, the bluer
the light. The lower the color temperature,
the redder the light is.