Unit 3 – Topic 4 Eyes & Cameras

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!

Light Entering Aperture

Light Entering Eye Camera Pupil Aperture Allows light in

Light Entering Pupil Aperture Eye Camera Little = small How much light depends on how much light is needed Eye Camera Pupil Aperture Little = small Allows light in Lots = big

Light Entering Lots = big Little = small How much light depends on how much light is needed Lots = big Little = small

Light Entering How is this all controlled? Eye = tiny muscles around the eye called the iris Colour of iris is your eye colour

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

Inside The Eye Light enters eye through pupil Light goes into the retina Retina is covered with photoreceptors

Inside The Eye Photoreceptors Rods Cones Two Types 3 Types Green Red Blue Two Types Rods Cones Sensitive to Light In low light only detect shades Operate in Low light Detect Colour

Inside The Eye

Inside The Eye Photoreceptors send messages to optic nerve Optic nerve sends messages to the brain Brain creates an image  film on camera

Light Entering

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

Focusing Light

Focusing Light

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

Correcting Vision Issues Most eye problems fall into two categories Nearsightedness Farsightedness Cannot see objects far away Cannot see objects close up

Correcting Vision Issues Lens not fat enough Lens not thin enough

Inside The Eye Why is the image upside down when it reaches the brain?

Laser Eye Surgery Used to replace the need for glasses/contacts Cuts flap in tissue Covering the eye Reshapes cornea Which acts as the new corrective lens Folded back so cornea is exposed Reshaped with UV light pulses

Laser Eye Surgery

Laser Eye Surgery

Laser Eye Surgery

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)

Night Vision Goggles

Camera Eyes We like to compare eyes vs. cameras If they have … Roughly round in shape Cornea Lens Retina We call them camera eyes

Camera Eyes They can vary Bees see UV light Can see different wavelengths Fish Birds Large lens (goes through pupil) Ultra sharp vision Allows them to see all directions More cones than humans

Camera Eyes Nocturnal Have more rods Acts like a mirror which reflects light Awake at night Large pupils (Capture more light) Tapetum Lucidum Extra layer in eye

Camera Eyes

Camera Eyes

Made up of many individual “eyes” Compound Eyes Made up of many individual “eyes” Each unit ommatidium Focusing cone Long Tube Lens on outer surface Light sensitive cell

Compound Eyes These eyes tend to be convex Makes them excellent at detecting motion

Compound Eyes There are some drawbacks Works like a TV / Pixels Difficult to form a single image Works like a TV / Pixels More ommatidium better image

Digital/Stadium Images Each card contains a coordinate When pieced together they form an image

The image is made up of pixels Digital Images Digital Images The process of creating an image using a computer The image is made up of pixels From the term Picture Elements Pic Ele

Colouring Digital Images Each pixel is given a value Each value corresponds to a colour That pixel then displays that colour

Many more small squares Image Quality Size of Pixel Large Small Many small squares Many more small squares Low resolution High resolution

Capturing A Digital Image Light Enters through aperture This can be stored and transmitted Converted to digital information Reaches a CCD (Charged-Couple Display) Small electrical current charges squares Like grid-paper

Transmitting Digital Transmission Can also see different light spectrums Information can be coded, transmitted coded, reassemble by a computer Without this we would not be able to transmit information anywhere