Prepared by:Gozon, Ma. Crystal Angelika O.
2PSED1
Light• One small part of a
spectrum of electromagnetic energy that surrounds us
Did you know?Light consists a set of electromagnetic waves which travel at a speed of around 186,000 miles per second.
Electromagnetic EnergyAll forms move in waves
Waves
S i r I s a a c N e w t o n
• Discovered that sunlight could be broken down into different colors by means of a triangular solid of glass called Prism
THE E Y E
External
Internal
Cornea
Sclera
Iris
Pupil
Lens
Aqueous Humour
HUMAN EYE AND ITS PARTS
HUMAN EYE AND ITS PARTS
RETINA
Bipolar Cells Ganglion Cells OPTIC NERVE
-the nerve that transmits sensory information from
the eye to the brain
HUMAN EYE AND ITS PARTS
Types of
Photoreceptors
Cones•-cone-shaped photo-
receptors that transmit sensations of color
Rod•-rod-shaped
photoreceptors that are sensitive only to the intensity of light
Types of PhotoreceptorsRods125 million rods are distributed across the retina
Allow us to see in black and white
More sensitive to dim light
Cones6.4 million cones are distributed across the retinaDensely packed in a small spot at the center of the retina called the Fovea
Visual acuity is greatest at this spot
Provides vision color
HUMAN EYE AND ITS PARTSVisual Acuity – sharpness of vision
Nearsighted/Myopia• a vision condition in which close objects are seen clearly,
but objects farther away appearFarsighted/Hyperopia
• a vision condition in which distant objects are usually seen clearly, but close ones do not come into proper focus
Blind Spot• the area of the retina where axons from ganglion cells meet
from the optic nerve
PresbyopiaA condition
characterized by brittleness of the lens
Light Adaptation
Dark Adaptation-the process of adjusting lower lighting
*Cones reach their max adaptation to darkness in about 10 minutes while Rod continue to adapt for 45 minutes or so.
Light Adaptation
Adapting to brighter conditions takes place more rapidly.
*At first you may be painfully surprised by the featureless blaze around you
Color Vision • is the ability of an organism to distinguish objects based on the wavelengths of the light they reflect, emit, or transmit.
Perceptual Dimensions of Color
Hue
Value
Saturation
Warm and Cool Colors
Complementary Colors
Afterimages
-the lingering visual impression made by a stimulus that has been removed
Theories of Color Vision 1. Trichromatic Theory-based on an experiment
conducted by Thomas Young, British scientist
-the theory that color vision is made possible by three types
-
Theories of Color Vision Hermann von
Helmholtz- German physiologist- The retina in the eye
must have 3 different types of color photoreceptors cones
Theories of Color Vision 2. Opponent-
process Theory- Ewald Hering, a
German physiologist -the theory that color
vision is made possible by three types
Perceptual Dimensions of Color
HueValue
Saturation
Color BlindnessTrichromat- A person with normal color visionMonochromat-A person who is sensitive to black and white
only and hence color-blindDichromats- A person who is sensitive to black-white and either
red-green or blue-yellow and hence partially color blind.
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VISUAL PERCEPTION
It is the process by which we organize or make sense of the sensory impressions caused by the light that strikes our eyes.
Perceptual Organization
Ambiguous - Capable of
being interpreted in various ways
Ambiguous
Laws of Perceptual Organization
• Closure• Similarity• Continuity• Proximity
Closure
Similarity
Continuity
Proximity
Top-Down
Perceive the whole and then individual parts
as needed
Input-data driven
Bottom-UpPerceive the
individual parts and organize them into a
whole, if possible
Information available in the stimulus itself
Perception of Motion
Sensations that give rise to misperceptions
Stroboscopic Motion• A series of stationary images that
are presented in rapid success
PERCEPT ION
Monocular Cues• Perspective• Relative size• Clearness• Overlapping• Shadows• Texture
Gradient
Binocular Cues
• Retinal Disparity
• Convergence
Size Constancy
Color-Brightness Constancy
Shape Constancy
Visual Illusions• The Hering-Helmholtz
Visual Illusions• The Muller-Lyer