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