Unit 3 Topic 4 Eyes Cameras Eyes vs

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

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 Photorecepto rs 3 Types - Green - Red - Blue Two Types Rods Sensitive to Light Operate in Low light Cones Detect Colour In low light only detect shades

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

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 • 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 Cannot see objects far away Farsightedness 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 Folded new corrective back so lens 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 Screen is covered in phosphor Which is why the image is green Phosphor glows green when hit with light

Night Vision Goggles

Camera Eyes We like to compare eyes vs. cameras If they have … Cornea Lens Retina 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 Birds Bees see UV light Can see different wavelength s Ultra sharp vision More cones than humans

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

Camera Eyes

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

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

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

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

Colouring 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 Low resolution Small Many more small squares High resolution

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

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