PO2 M4: Color Vision

Monochromacy

Seeing in shades of grey due to cone dysfunction

299, 792, 458 m/s

Speed of light

Photons

Electrical fields travelling through space

Photons

Mass-less particles of light traveling through space

Wavelength

Distance between crest to crest or trough to trough of light. Measured in meters

Amplitude

Height of crest or depth of trough of light waves

Frequency

Number of wavelengths in a period, inversely related to wavelength

Energy

Measured in electron volts (eV), a property of light

Visible Spectrum

Narrow portion of electromagnetic spectrum seen by human eye

Newton

Identified the ROYGBIV colors that make up the visible spectrum through the use of Prism

Dispersion

Colors in the visible spectrum was discovered through this phenomenon. It is the bending of light into its component colors.

Dispersion

Phenomenon using prisms to separate light into colors

Opticks

It is the book that documented Newton's discoveries from his experiments on light passing through prism

Colors

That aspect of things is caused by different qualities of the light reflected or emitted by an object, definable by the observer

Hue, Lightness, Saturation

That aspect of things is caused by different qualities of the light reflected or emitted by an object, definable by the observer in terms of (3 answers)

Colors

The Characteristic of light by which an individual is made aware of the objects through the receptors of the eye, definable by the observer

Wavelength, Luminance, Purity

The Characteristic of light by which an individual is made aware of the objects through the receptors of the eye, definable by the observer in terms of (3 answers)

Sparks our emotions Influence our moods Gives symbolic meaning Influences our purchases Used to define contours Helps us remember objects Helps us judge properties Part of our experience

Functions of Colors (8 answers)

Perspective of the Observer and perspective of the thing looked at

Color is definable by what? (2 Answers)

Chromacity

Other term for Qualities or Properties of Color

Hue, Brightness, Saturation, Temperature

Qualities of Color (4 Answers)

Hue

Familiar color's name / family linked directly to its wavelength

Luminance

Apparent intensity or brightness of a color

Brightness

Darkness or lightness of a color

Luminosity, Luminance, Value

Other terms for Brightness (3 Answers)

Yellow-White

As intensity or brightness increases, all hues appear what?

Achromatic

As intensity or brightness decreases all hues appear what?

Achromatic

Hue becomes black

Saturation

Purity of a color, 0% means black, 100% means white

Saturation

The dilution of hue by white. Also the addition of white for it to become less saturated

Chroma

Other term for Saturation

Temperature

IT is the warmness or coolness of colors

Red, Blue, Green

The primary colors

Magenta, Yellow, Cyan

Secondary Colors

Blue and Red

Magenta is made up of what colors?

Green and Red

Yellow is made up of what colors?

Green and Blue

Cyan is made up of what colors

Physics of the objects relative to the environment and Characteristics of the perceiving eye and personal contextual cues

This are the 2 things that Color of Objects depend on

Physics of the objects relative to the environment

The spectrum of the incident light, reflectance properties (Material and its physical and chemical state, the surface roughness, and geometric circumstances - light angle of incidence) of the surface

Chromatic adaptation and Color constancy

2 things under the characteristics of perceiving eye and personal contextual cues

Chromatic Adaptation

Ability to adjust to changes in illumination to preserve object colors

Color Constancy

Ability in perceiving colors as constant despite varying illuminations

L, M, S cones

3 cones

Color Vision

Ability to discriminate various wavelengths independent of light intensity

Color Vision

the ability to discriminate among stimuli on the basis of hue, independent of brightness or any other cue

Effective energy of light and the properties of light

Color vision uses what to create color?

Physiological and Psychological Aspect

2 aspects of Color Vision

Physiological Aspect

Measure of Visual function at the photoreceptor level

Physiological Aspect

Aspect of color vision responsible for colorimetry

Physiological aspect

Aspect of color vision responsible for Color encoding

Psychological Aspect

Measure of cortical function at the later stages of visual processing

Psychological Aspect

Color perception affected by surround stimulus, adaptation, and experience

Psychological Aspect

Aspect of Color vision responsible for Color discrimination and Color Constancy

Physiological Aspect

It serves in the retinal function of the eye

Positive and Negative After-image

Continuation of visual sensation after stimulus removal

Color Context/ Chromatic Contrast/ Chromatic Induction or Setting Prior Exposure to Stimulus

2 Factors affecting Color Perception

Color Context

The appearance of color is altered by introducing a second surrounding color

Prior Exposure to Stimulus

Processes of adaptation constantly adjust visual sensitivity according to the stimulus the observer is currently viewing

Colorimetry

Science of technology that quantifies and physically describe human color perception

Colorimetry

It includes the perception of color by the human eye and brain, the origin of color in materials, and the physics of visible electromagnetic spectrum

Science of Color or Color Science

Other Terms for Colorimetry

The International Commission on Illumination

is a technical, scientific and cultural non-profit organization whose objective embraces fundamental subjects as vision, photometry and colorimetry

Commission Internationale de l'Eclairage

Other Term for The International Commission on Illumination

Color Discrimination and Color Constancy

What are the 2 distinct visual functions supported by color vision

Color Discrimination

ability to determine the 2 spectra. identify or detect color and differentiate it with other color

Color Constancy

ability to identify object on the basis of their color appearance

Short Cones

Cone sensitive to blue color

440-450 nm

Specific wavelength short cones are sensitive to

Medium Cones

Cones sensitive to green color

535-550 nm

Specific wavelength medium cones are sensitive to

Long cones

Cones sensitive to red color

570-590 nm

specific wavelength long cones are sensitive to

Reasons for anomalies in Color Vision

Chromatic Adaptation and Color Naming

2 Color Vision Process

Chromatic Adaptation

Surface based processing similar to color constancy and happens internally

Chromatic Adaptation

Process of favourable or useful adjustment of sensory processes to compensate for changes in the spectral quality of light source in order to keep visual perception of colour approximately constant

Color Naming

Identifying colors based on memory and categorization

Color Naming

Category based processing and happens externally.

Physical color mixing, Physiological, and Juxtaposition

Types of Color Mixing

Physical Color Mixing

Physically combining colors to create new hues

Additive Colors and Subtractive Color

2 types of Physical Mixing

White, Lights

Additive color will result to what color? where can you use it?

Black, Pigment

Subtractive Colors will result to what color? where can you use it?

Physiological

Color mixing that is based on positive after image

Positive and Negative After-image

Continuation of a visual sensation after stimulus removal

Juxtaposition

Based on the positioning of colors, the arranging of different colors side-by-side to create optical effects in a viewer's eye.

Juxtaposition

The viewer perceives color in an image as a result of two or more colors that are positioned next to, or near each other.

Optical Color Mixing

Other term for Juxtaposition

Chromatic Induction

An example of Justaposition

Chromatic Induction

Creating perceived colors through color positioning

Trichromatic Theory

States that there are three receptors in the retina that are responsible for color perception and the combination of these three colors produce all of the colors that are perceived

Three Component Theory

Other term of Trichromatic Theory

Thomas Young and Hermann von Helmholtz

Founders of Trichromatic Theory

Thomas Young

in 1802 he suggested that the eye contained different photoreceptor cells that where sensitive to different wavelengths of light in the visible spectrum

Hermann von Helmholtz

in mid-1800 he suggested that the cone receptors of the eye were either short-wavelength (Blue), medium-wavelength (green), or long-wavelength; and that the strength of the signals detected by the receptor cells determined how the brain interpret color in the environment.

Erythrolabe, Chlorolabe, Cyanolabe

The three color sensations

Trichromatic Theory

There are three only (3) primary colors but many hues

Opponent Process Theory

States that the ability to perceive color is controlled by three receptor complexes with opposing actions

Edward Hering

Founder of Opponent Process Theory

Red-green complex Blue-yellow complex Black-white complex

Three Receptor Complexes