Unit 3 – Topic 4 Eyes & Cameras
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Transcript of Unit 3 – Topic 4 Eyes & Cameras
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Unit 3 – Topic 4Eyes & Cameras
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Eyes vs. Camera
• You can think of the eye & camera as an “image producing” technologies– 1 is natural – 1 is artificial
• Cameras are built on the principles of human sight – Their components are very
comparable!
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Light Entering
Eye Camera
Pupil Aperture
Allows light in
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Light Entering
Eye Camera
Pupil Aperture
Allows light in
How much light depends on how much light is needed
Lots = big
Little = small
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Light Entering
• How is this all controlled? • Eye = tiny muscles around the
eye called the iris• Colour
of irisis youreye colour
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Light Entering
• How is this all controlled? • Camera = cylinder or dial around
the aperture that when turned increases or decreases the size of the aperture
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Inside The Eye
• Light enters eye through pupil
• Light goes into the retina
• Retina is covered with photoreceptors
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Inside The Eye
Two Types
Photoreceptors
Rods
Cones
Sensitive to Light
Operate in Low light
DetectColour
In low lightonly detect shades
3 Types- Green- Red- Blue
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Inside The Eye
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Inside The Eye
• Photoreceptors send messages to optic nerve
• Optic nerve sends messages to the brain
• Brain creates an image film on camera
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Focusing Light
• Eyes & Cameras have transparent lenses
• Lens must be in right position to sharpen image (double convex)
• Muscles attached to lens (ciliary muscles) contract to lengthen & relax to shorten
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Focusing Light
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Focusing Light
• Changing the shape of lens focuses the image on the retina
• Cameras do this automatically when they have the auto-focus feature & can be done manually
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Correcting Vision Issues
Most eye problems fall into two categories
Nearsightedness Farsightedness
Cannot see objectsfar away
Cannot see objectsclose up
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Correcting Vision Issues
Lens not fat enough
Lens not thin enough
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Laser Eye Surgery
Used to replace the need for glasses/contacts
Reshapes corneaCuts flap in tissue Covering the eye
Which acts as thenew correctivelens
Folded back so corneais exposed
Reshaped with UV light pulses
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Laser Eye Surgery
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Night Vision Goggles
2 Lenses and 1 Viewing Screen
In general they intensify an image and project it on to a screen
Which is why the image is green
Screen is covered in phosphor
Phosphor glows green when hit with light (particles)
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Night Vision Goggles
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Camera Eyes
We like to compare eyes vs. cameras
If they have …
RetinaCornea
LensRoughly round in shape
We call them camera eyes
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Camera Eyes
They can vary
Fish
Large lens (goes through pupil) Allows them
to see all directions
Birds
Ultra sharp vision
More cones than humans
Can see different wavelengths
Bees see UV light
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Camera Eyes
Nocturnal
Awake at night
Large pupils (Capture more light) Extra layer in
eye
Tapetum Lucidum
Acts like a mirror which reflects light
Have more rods
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Camera Eyes
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Compound EyesMade up of
many individual
“eyes”Each unit ommatidium
Long Tube
Lens on
outer surfac
e
Focusing cone
Light sensitive cell
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Compound EyesThese eyes tend to be convex
Makes them excellent at detecting motion
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Compound EyesThere are some drawbacks Difficult to form a single image
Works like a TV / Pixels
More ommatidium better image
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Digital/Stadium Images
Stadium Image
Each card contains a coordinate
When pieced together they form an image
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Digital ImagesDigital Images
The process of creating an image using a computer
The image is made up of
pixels
From the term
Picture Elements
Pic Ele
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Colouring Digital Images
Digital Images
Each pixel is given a value
Each value corresponds to a colour
That pixel then displays that colour
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Image QualitySize of Pixel
Large
Many smallsquares
Small
Many more small squares
Low resolution High resolution
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Capturing A Digital Image
Light Enters through aperture
Converted to digital information
Reaches a CCD(Charged-CoupleDisplay) Like grid-paper
Small electrical current chargessquares
This can be stored and transmitted
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TransmittingDigital Transmission
Information can be coded, transmitted coded, reassemble by a computerWithout this we would
not be able to transmit information anywhere
Can also see different light spectrums