Week 3 Colour Perceptiom Flashcards
What is the primary function of colour perception?
To distinguish two surfaces with the same brightness by providing information about hue, saturation, and brightness.
What are the three components of colour sensation?
Hue (e.g., red, blue).
Saturation (purity of the colour).
Brightness.
What are the physical properties of colour?
Wavelength (e.g., blue: 450–490 nm, green: 500–575 nm, red: 620–700 nm).
Intensity (light level).
What is the difference between chromatic and achromatic light?
Chromatic light: Some wavelengths are reflected more than others.
Achromatic light: All wavelengths are equally distributed (e.g., white light).
What is additive colour mixing?
The process where new wavelengths are created by combining light sources, e.g., adding red, green, and blue spotlights to produce white.
What is subtractive colour mixing?
The process of mixing pigments, where more light is absorbed and fewer wavelengths are reflected (e.g., mixing cyan and magenta to create blue).
What are the three types of cone photoreceptors, and what wavelengths do they absorb?
S cones: Short wavelengths (419 nm).
M cones: Medium wavelengths (531 nm).
L cones: Long wavelengths (558 nm).
Where are cone photoreceptors most concentrated?
Around the fovea, leading to better colour discrimination in central vision.
What is the opponent-process theory?
A theory where ganglion cells combine signals from cones to form opponent channels, such as blue-yellow and red-green, enhancing colour contrast.
How do ganglion cells contribute to colour perception?
By grouping cone signals into opponent channels, e.g., a B+Y− channel where blue enhances the response, and yellow inhibits it.
What are the three types of colour deficiencies?
Protanopia: Missing long wavelengths (red).
Deuteranopia: Missing medium wavelengths (green).
Tritanopia: Missing short wavelengths (blue).
What is the Ishihara test used for?
Detecting colour deficiencies through pseudo-isochromatic plates with numbers visible only to those with normal colour vision.
What is colour constancy?
The ability to perceive consistent object colours under varying lighting conditions by estimating reflectance.
