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 Eye Camera Pupil Aperture Allows light in 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 Two Types Photoreceptors Rods Cones Sensitive to Light Operate in Low light Detect Colour In low light only detect shades 3 Types -Green -Red -Blue
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
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 Reshapes cornea Cuts flap in tissue Covering the eye Which acts as the new corrective lens Folded back so cornea is exposed Reshaped with UV light pulses
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 … Retina Cornea Lens Roughly round in shape We call them camera eyes
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
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
Camera Eyes
Compound Eyes Made up of many individual “eyes” Each unit ommatidium Long Tube Lens on outer surface Focusing cone Light sensitive cell
Compound Eyes These eyes tend to be convex Makes them excellent at detecting motion
Compound Eyes There are some drawbacks Difficult to form a single image Works like a TV / Pixels More ommatidium better image
Digital/Stadium Images Stadium Image Each card contains a coordinate When pieced together they form an image
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 Digital Images Each pixel is given a value Each value corresponds to a colour That pixel then displays that colour
Image Quality Size of Pixel Large Many small squares Small Many more small squares Low resolutionHigh resolution
Capturing A Digital Image Light Enters through aperture Converted to digital information Reaches a CCD (Charged-Couple Display) Like grid-paper Small electrical current charges squares This can be stored and transmitted
Transmitting Digital Transmission Information can be coded, transmitted coded, reassemble by a computer Without this we would not be able to transmit information anywhere Can also see different light spectrums