Flashcards in Lecture 19 - Lecture 21: Vision Deck (79):
Light is a form of electromagnetic radiation generated by the oscillation of electrically charged particles called __________?
What are the two most important qualities we perceive from light?
Color and brightness
The length of the light's wavelength produces
As the length of the light wave increases, ___________________________
The sensation of the color changes
The brightness of a couloir is related to it's ____________, which is directly proportional to the density of photons in the wave.
The more photons in the wave, (brighter/lighter) the light or color will appear to be.
Light is a pattern of _________________ and _______________, along the many wavelength they create, that allow us to see the shapes and surfaces of objects.
Reflection and absorption
What is used to measure light?
Tendency for colors to remain fix despite changes in illumination In which they are embedded
Two types of reflection
1. Speculation reflection
2. Diffuse reflection
What is specular reflection
Mirror like reflection
What is diffuse reflection
Reflection of the rough
The first step in color perception begins with the _________ in the retina
What are the 3 different types of cones?
1. Absorbs light in short wavelengths (445 nm-blue)
2. Absorbs light at medium wavelengths (535nm-green)
3. Absorbs light at long wavelengths (570nm-red)
Red sensitive cones do not respond exclusively to long wavelengths of light, they just respond better - the same principle holds for the other 2 cones p. 71
We detect all these different wavelengths because the light energy reaching our eyes is __________ by the cones into neural impulses
______________ are special molecules imbedded in their membrane consisting of opsin and retinal
What are the 3 trichromatic colors?
Red, green, and blue
The trichromatic theory is also known as?
What is the problem with the trichromatic theory?
It could not explain the effect of negative after-images
What is the most common form of color blindness
Red (protanopia) - green (dueteranopia)
followed by the rarer blue-yellow form
(no such thing as red -blue or green-yellow color blindness)
Who proposed the opponent theory of color vision
Where does yellow come from?
It is made up from inputs arriving from the red and green cones
The perceived color of an object remains the same under very difficult lighting conditions
What colors do people who suffers are red-green color blind sees?
Blue, yellow, and grey
Why does red-green color blindness predominantly affect the males
Because the protan and duet an genes are located on the X-chromosomes, of which men have one and women have two. Women are rarely red-green blind because if one of their X chromosome is defective the other one can compensate for it. Daughters of men who handed down color blindness to his children will normally be unaffected
What type of color blindness would it be if a person lacks blue cones (unable to distinguish between blue and yellow).
_________________ causes total color blindness
First region to receive input from the lateral geniculate nucleus
Visual area 1 or v1 or area17 or primary visual cortex
18 and 19 or V2 and V3 make up the visual association cortex
Condition where people suffer from bilateral damage to the posterior regions of the parietal lobes
Difficulty in shifting one's gaze into a new stimulus. Difficulty in focusing in on a particular object. Their eyes wander around so that objects came into view for a while and are then replaced by others
Inability to reach for objects under visual guidance. Result to person fumbling and misreaching for objects and being unable to point accurately to a visual stimulus although the they can see it clearly
A person's inability to see the totality of their visual scene. Have a very narrow visual attention field which will result in their being unable to see two objects at once. E.g. Toothbrush and pen
A person being unable to recognize the faces of their family and friends
The stimulus for activity ting the visual system is ________?
What makes a colored objected appear to be that color (I.e. Blue)?
When light strikes an object, the long wavelength is reflected and the other wavelength is absorbed
Sensitive to light at low energy
What are combined pigments?
Selectively removing all the wavelengths of light
What are the 2 main receptor types
What is the difference between cones and rods
Cones - daylight; gives color
Rods - nighttime
*cones sensitivity to light is lower than the rods
What are the 4 receptors
1. Short wavelengths (445 nm-blue)
2.medium wavelengths (535nm-green)
3. long wavelengths (570nm-red)
What the peak of the cone tells you?
What states that all absorbed photons generate the same response independently of wavelength
Principle of univariance
________________ same pattern of activation in the cone and will have the same colour experience.
- why monitors, colored TVs, cameras, etc. work
_______ is all about trichromatic. Type of adaptation. Receptors become unresponsive
Color after image
What are the 3 opponent aces that you need? And what is the neutral color?
-Grey is neutral
What is color?
Capacity to experience differences between wavelengths
Why do you experience color?
Because you have more than 1 cone while rods look at the same visible spectrum
What is color vision?
Capacity to experience different wavelength of light
What does trichromatic count for?
What is a single wavelength of light
Mixing colors from any points on the opposite sides of the perimeter takes you through a __________. What colour is it?
Neutral point; grey
What theory states that certain colors cancels each other out
Opponent process theory
What corresponds grossly to the height of the 3D representation?
Corresponds to the radial distance from the achromatic point
Equal intensity plane of colour space
What colors you get from an unusual spectrum
The 4 colors: red, green, blue and yellow are part of the spectral locus
What do you mean by impure red?
Impure because it's a mixture of red and blue
A color that is evoked by a single wavelength of light in the visible spectrum
Most saturated point
Subtractive color can be used for?
What is used for printing?
Used for presentations?
What is the principle that says that it has the same colour but the surround affects it?
How do you decompose luminance into their physical sources?
What are shadows?
Difference on how they are illuminated
What are the 4 edge classification problem?
1. Reflectance (changes in surface lightness or color)
2. Shape (folds)
3. Illumination (shadows; spotlights)
4. Occlusions (which could include one or more f the above)
What is illiuminance
Light falling on a surface
What is reflectance?
Proportion or percentage of light that a surface reflects
What is luminance?
Total amount of light reaching the eye
What is the formula for luminance
Luminance = illiuminance X reflectance
What is important about shadows?
The edge of the shadow
Yellow and blue will give you what color?
what is a single (different) wavelength of light at a particular intensity (say 550)
what do you call the total response in all lights of each individual wavelength?
what does photoreceptor curves mean?
the curve tells the weights of the wavelength
how many receptors do you need to tell about the wavelength composition of light?
you need the 3 receptors/cones
what do you experience when you excite the cones in the same way. Thi is why monitors, TV's, colour cameras film, etc worl