Mechanisms of color perception Flashcards
True/False? All light sources give the same spectrum of light
False
What is specular reflection? What is body reflection?
Specular reflection is the reflection of light (incident angle = reflected angle)
Body reflection is reflection inside the body or outside (incident angle != reflected angle)
If Red, Green and Blue light are shone on Cyan, Magenta, and Yellow materials, which rays would be reflected for each?
C: GB (R absorbed)
M: RB (G absorbed)
Y: RG (B absorbed)
How does natural color vision work (compared to synthetic displays?)
Subtractive mixing (compared to additive mixing) Function of emission spectra of light source and reflectance properties of materials
What are 3 different Color spaces?
RGB (displays)
CMYK (printing)
HSV (psychologically relevant representations)
What is trichromacy?
Any hue can be reproduced by mixing three primary colors (red green and blue)
What is the optimal color for
S-Cones?
M-Cones?
L-Cones?
Blue
Green
Red
What is the problem with trichromacy?
It doesn’t explain color opponency
What is color opponency?
White/Black
Blue/Yellow
Green/Red
Each is a combination of excitatory/inhibitory neurons connected to M/L/S cones
Which Cones are present for Red/Green color opponents?
M (I), outer
L (E), inner
L and M are flipped for Green/Red
Which cones are present for Blue/Yellow Color opponents?
M (I), outer
L (I), outer
S (E), inner
S and (L,M) are flipped for Y/B
Which cones are present for Light/Dark color opponents?
M (I/E), inner/outer
L (I/E), inner/outer
Same as dark/light color opponents
Where are color opponent cells found?
LGN and retina
What color opponent cells do midget cells connect to? what do they discriminate?
Midget -> Parvocellular: Red-green
What color opponent cells do Bistratified cells connect to? what do they discriminate?
Bistratified -> Koniocellular: Yellow-Blue
What color opponent cells do Parasol cells connect to? what do they discriminate?
Parasol -> Magnocellular: Not chromatic
Achromatic signals are conveyed by which cells?
Parasol, midget and bistratified
What kind of color opponency is found in Retina and LGN and what is its function?
What kind of color opponency is found in Cortex and what is its function?
Single opponency, coding for presence of color
Double opponency, allows for computation of color contrast
