9: Colour Perception Flashcards
According to Newton, white light is made up of different _____, of which long ones show less _____ than short.
Wavelengths; refraction.
What is reflectance? What does it mean to say coloured objects exhibit selective reflectance?
Reflectance: amount of incident light that is reflected off the object.
E.g., red objects selectively reflect longer wavelengths.
What is selective transmission?
Allow only select wavelengths to pass through.
Reflectance curves plot the % reflectance at each wavelength. Coloured objects have what? Black/gray/white?
Colored objects will have a peak in the reflectance curve.
Black/gray/white have flat reflectance curves.
Transparent colored objects can be similarly described with _____.
Transmission curves.
Mixing paints is what?
Subtractive colour mixing.
Mixing light is what?
Additive colour mixing.
What is intensity?
Values or brightness.
What is wavelength?
Hue.
Shades of grey are what colours?
Achromatic.
Colours aside from shades of grey are what?
Chromatic or spectral.
Why are nonspectral colours not on the spectrum?
Are a mixture of colors (e.g. brown).
How many steps of wavelength can we see? Value? Saturation? How many colours total does that equal?
200, 500, 20.
2 million colours.
Hue, value, and saturation can be organized into what? What defines it?
Colour solid.
Coordinates within space define the colour, based on perceived colour. Does not include nonspectral colours.
Since wavelengths do not have colour, how do we distinguish wavelengths of light?
Have sensors. Colour is the brain’s way of informing us what wavelengths are present.
What is psychophysical evidence for the trichromatic theory of colour vision?
The color of a monochromatic test light can be matched by mixing lights of any three wavelengths.
Two lights that appear identical even though they have a different wavelength composition are called what?
Metameric pairs.
