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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.
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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 Aperture How much light depends on how much light is needed Little = small Lots = big Allows light in
Light Entering • How is this all controlled? • Eye = tiny muscles around the eye called the iris • Colourof irisis youreye 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 Two Types • 3 Types • Green • Red • Blue Rods Cones In low lightonly detect shades Sensitive to Light Operate in Low light DetectColour
Inside The Eye • Photoreceptors send messages to optic nerve • Optic nerve sends messages to the brain • Brain creates an image film on camera
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 objectsfar away Cannot see objectsclose 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
Night Vision Goggles 2 Lenses and 1 Viewing Screen Which is why the image is green In general they intensify an image and project it on to a screen Screen is covered in phosphor Phosphor glows green when hit with light (particles)
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 Bees see UV light They can vary Can see different wavelengths Fish Birds Large lens (goes through pupil) Ultra sharp vision More cones than humans Allows them to see all directions
Camera Eyes Have more rods Nocturnal Acts like a mirror which reflects light Awake at night Large pupils (Capture more light) TapetumLucidum Extra layer in eye
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 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 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 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 Small electrical current charges squares Reaches a CCD (Charged-CoupleDisplay) 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