COLOR VISION Flashcards
that aspect of things that is caused by differing qualities of the light reflected or emitted by an object, definable in terms of the observer.
Colors
-Science of Color
-the perception of color by the human eye and brain, the origin of color in
materials, and the physics of electromagnetic radiation in the visible range
Chromatics, colorimetry, or simply color science
range of wavelength in which the human eye can perceive
within 390 nm to 700 nm
a color that is evoked by a single wavelength of light in the visible spectrum,
or by a relatively narrow band of wavelengths
Spectral Colors
a process that allows the brain to recognize a familiar object as being consistent color regardless of the amount of light reflecting from it at a given moment
Color constancy
He suggests that both the eye and the brain are involve in
color constancy
Edwin H Land
The ability of the human eye to distinguish colors is based upon the varying sensitivity of
photoreceptors in the retina particularly the cones to light of different wavelengths.
Trichromatic Theory
Found the Trichromatic Theory
Thomas young
most responsive to light that we perceive as blue
or blue-violet, with wavelengths around 450 nm
Short-wavelength cones, S cones, or blue cone
most sensitive to light perceived as green,
with wavelengths around 540 nm
middle-wavelength cones, M cones, or green cones
most sensitive with wavelengths around
570 nm.
long-wavelength cones, L cones, or red cones
values in which For each location in the visual field, the three types of cones yield three signals based on the
extent to which each is stimulated.
tristimulus values
region of luminance levels and color temperatures that is considered pleasing
middle region
region of luminance levels and color temperatures that is considered cold and dim
lower region
region of luminance levels and color temperatures that are warm and colorful
upper region
As luminance decreases, the visual system switches from cone-dominated vision to rod-
dominated
purkinje phenomenon/effect
the ability to discriminate light on the basis of wavelength composition
COLOR VISION
Theory that says the retina has 3 types of cones responsible for color vision
each cone is named according to the wavelength they are sensitive with
TRICHROMACY THEORY
Reduced or complete loss of color discrimination
ACHROMATOPSIA
- perceive everything just in shades of gray
- more commonly referred to as total color blindness
Monochromacy
the condition of having only a single type of cone in the retina
(incomplete achromatopsia)
Cone monochromacy
all types of cones are either non functional or missing
(complete achromatopsia)
Rod monochromacy
symptoms of rod monochromacy
- completely unable to distinguish colors
- reduced VA
- Hemeralopia (severe light sensitivity)
- nystagmus
- central scotoma
an uknown number of women may perceive millions of colors invisible to the rest of us
Tetrachromacy
theory suggests that there are three opponent channels: red versus green, blue versus yellow, and black versus white
Opponent theory of colors
Japanese ophthalmologist who created the Ishihara color test to detect colour blindness.
Dr. Shinobu Ishihara
in this ishihara plate, individuals with color vision defect should see a different figure from individuals with color vision
Transformation plates
in this ishihara plate, only individuals with normal color vision could recognize the figure
Vanishing plates
in this ishihara plate, only individuals with color vision defect could recognize the figure
Hidden digit plates
in this ishihara plate, intended to determine the type of color vision defect and the severity of it
Diagnostic plates
this test was first produced in 1954 and can be used to classify all 3 different forms of color vision deficiency
Hardy-Rand-Rittler test
- test to classify color vision defects by using a set of discs
- each set contains a reference disc and 15 numbered discs which make up an incomplete color circle
Farnsworth d15 Dichotomous test
- accomplished by the arrangement of unsaturated colored discs
- this test is not appropriate for patients who already failed the Farnsworth D15 test
- specially designed to simulate signals and are most often used as vocational test
- allows testing the required ability of patients directly
- they have high practical value
- it doesn’t reveal the nature and severity of the color vision defect
Lanthony Desaturated D15
- this lantern includes two different green, two red and a white light
- lights are show in pairs of two, low or high brightness, either vertically or horizontally aligned
- the test person is asked to name the colors
Holmes-wright Lanterns
- the standard test in the US.
- specially designed to pass people with mild form of color vision deficiency
Farnsworth Lantern (Falant)
provides the most accurate way to test the severity of color blindness and distinguish between dichromats and anomalous trichromats
Anomaloscope
test wherein a mixture of red and green light sources has to be matched with a yellow light source
Rayleigh Match
(blue-green) to test for tritan defects
Moreland Match
channels of opponent theory of colors
- red-green channel
- blue-yellow channel
- black-white channel
perceiving letters or numbers leads to experience of seeing colors
grapheme-color synesthesia
hearing musical sounds will lead to the unusual additional experiences of seeing colors
music-color synesthesia
• Is the first and fundamental quality of all colors
• Determined by the wavelength and therefore gives
rise to the characteristic series of sensation when
we view the specturm
Hue or Tone
In the Solar Spectrum, there are a number of Dark Lines known as the?
FRAUNHOFER Lines
the minimum stimulus necessary to cause a sensation
of lights (or the minimum visible of scotopic vision) is
called?
GENERAL OR ACHROMATIC LIGHT
THRESHOLD
the minimum intensity of light which is needed to make
the color discernable is known as the
SPECIFIC OR
CHROMATIC LIGHT THRESHOLD.
the interval between achromatic and chromatic light threshold is called the?
PHOTOCHROMATIC INTERVAL
- purity of colors
- freedom from a mixture with light
*
Saturation
term used to describe color that is less than saturated, color that has been dulled down.
desaturated color
color that contains one wavelength of high intensity
Saturated color
- is an attribute of visual perception in which a source appears to be radiation or reflecting light
- luminance
Brightness
- mixing of colors generally involves mixing colors of light
- in the absence of color results to black
- if all three primary colors are present the result is white
- used in television and computer monitors to produce a wide range of colors using only three primary colors
- in the absence of color results to black
Additive color mixing
- done by selectively removing certain colors
- the absence of color is white and the presence of all three primary colors is black
- used to create a variety of colors when printing on paper by combining a small number of ink colors, and also when painting
Subtractive color mixing
numbers of rods in eye
130 million
numbers of cones in eye
6-7 million
visual cell wherein pick of absorption is more on longer wavelength
cones
visual cell wherein pick of absorption is more on the shorter wavelength
Rods
damage in this area caused yellow-blue anomalies
Lesion in Choroid
damage in this area caused yellow-blue and red-green anomalies
Lesion in the Retina
damage in this area caused red-green anomalies
Lesion in optic nerve
Tests for color vision
- Pseudo-isochromatic plates
- arrangement tests
- Lantern tests
- anomaloscope
other term for rhodopsin
Visual Purple
other term for photopsin
Visual yellow or iodopsin
the observer perceives apple as red because?
- erythrolabe are stimulated
- blue and green are absorbed
a green mango is perceived green because?
chlorolabe are stimulated
an observer perceives the sky blue because?
cyanolabe are stimulated
using the additive method of color mixing, red + green results to?
yellow
using the additive color mixing, green + blue results to?
cyan
using the additive method of color mixing, red + blue + green results to?
white
when the blue-yellow compound undergo anabolic change, the result is?
blue
when the red-green compound undergo anabolic change, the result is?
green
when the black-white compound undergo anabolic change, the result is?
black
using the subtractive method of color mixing, yellow + magenta results to?
red
using the subtractive method of color mixing, cyan + yellow results to?
green
using the subtractive method of color mixing, cyan + magenta results to?
blue
when the blue-yellow compound undergo ketabolic change, the result is?
yellow
when the black-white compound undergo ketabolic change, the result is?
white
when the red-green compound undergo ketabolic change, the result is?
red
if light stimulates erythrolabe, the resulting sensation is?
red
if light stimulates chlorolabe, the resulting sensation is?
green
if light stimulates cyanolabe, the resulting sensation is?
blue
physiological method of color mixing is based upon?
Positive and Negative AFTER IMAGE
this color characteristic refers to its purity
hue
this color characteristic refers to its luminosity
Intensity
in the COLOR WHEEL, combining red and yellow will result to?
Orange
in the color wheel, combining yellow and blue results to?
green
in the COLOR WHEEL, combining red and blue will result to?
violet
Tertiary color is
mixture of 1 primary and 1 secondary colors
