Color Vision 1

In color __________, we start with black and add colored light to it. In color __________, we start with white and add filters to absorb some wavelengths and reflect others.

addition, subtraction

RGB is __________, while CMYK is __________.

additive, subtractive

In the Munsell Colorimetric System, value is on a scale of 0 to 10, where black is _____ and white is _____.

black = 0, white = 10

What does the Planckian locus on the CIE Chromaticity Diagram represent?

colors of blackbody radiators raised to a certain temperature

To find the complementary wavelength on a CIE Chromaticity Diagram, draw a line from the _________, through the __________, to the __________.

wavelength, white, opposite side of the diagram

To find the dominant wavelength on a CIE Chromaticity Diagram, draw a line from _________, through the __________, to the __________.

white, color, spectral locus

What is the equation for color purity?

cp = Lλ / (Lλ + Lw) Lλ = luminance of wavelength Lw = luminance of white light

blue + green = __________ red + blue = __________ red + green = __________

cyan, magenta, yellow

What is the Associative Property of Metamers?

If a 3rd metamer is created for one of a pair of metamers, all 3 will be metamers

What is the Additive Property of Metamers?

If we add the same wavelength to two metamers, the results will still be metamers

What is the Scalar Property of Metamers?

If we increase the intensity of two metamers, they will still be metamers

__________ is related to the wavelength of the light emitted, while __________ is related to the wavelengths of light reflected from an object.

Illuminant color, object color

How is non-spectral color obtained?

It is not present in sunlight, so it must be obtained by mixing spectral colors (Non-spectral colors are usually shades of purples)

What are MacAdam ellipses on a CIE Chromaticity Diagram?

Just noticeable differences in color for a person with normal color vision

Why was a RGB color-matching function not ideal?

Red has a tristimulus value below zero. Researchers didn't like this, because they only want to add colors, not subtract. They transformed the RGB function into the XYZ function.

In the Munsell Colorimetric System, chroma is labelled from 0 to 30+ and a higher number means __________ saturation.

more

Wavelength is a __________ attribute, while color is a __________ attribute.

physical, perceptual

Once a quantum of light is absorbed, all information about the wavelength is lost. If this is true, how do we distinguish colors?

The absorption of a long wavelength has the same effect as the absorption or a short wavelength, but the probability of absorption changes with wavelength and photoreceptor type.

What is color gamut?

The full range of colors that can be obtained from all possible mixtures of a specified set of primary colors

What is saturation?

-Degree to which a color appears to differ from an equally bright gray. -A color's perceived colorimetric purity

What are 3 perceptual attributes of color?

-Hue -Brightness -Saturation

What are the 3 parts of the Munsell Colorimetric System?

-Hue sectors -Chroma (saturation) -Value (lightness, intensity)

What are the 3 Grassman Laws?

-Scalar Property of Metamers -Additive Property of Metamers -Associative Property of Metamers

What are 3 loci found on the CIE Chromaticity Diagram?

-Spectral locus -Purple locus -Planckian locus

What is a colorimetric purity?

-The physical correlate of saturation -Describes the proportion of pure dominant spectral wavelength energy relative to the amount of achromatic luminance objectively present in a color sample

A person with normal color vision needs to mix only _____ __________ colors in different proportions to match any color.

3 primary

What are tristimulus values?

A set of 3 values that specifies the proportion of each primary color needed for a specific wavelength. The values add up to 1.0.

What are complementary colors?

Any two colors that produce a neutral color when added (Neutral colors: white, grey, black)

Light is projected through two different color filters and combined on a screen. Is this color addition or color subtraction?

Color addition

A light is projected through two colored filters placed in sequence and the color is projected onto a screen. Is this color addition or color subtraction?

Color subtraction. Filters subtract light!

In the Munsell Colorimetric System, how are the hue sectors divided up?

Each color is divided into 10 equally distinguishable steps and numbered 1 to 10. Example: Middle of the red sector is 5R

True or False: Pouring red water and blue water into the same cup to produce purple water is color addition.

False, it is color subtraction. The water is absorbing more and reflecting less photons.

True or False: All cones are able to absorb green light, its just that M-cones have a higher probability of absorbing green light.

True

True or False: Color perception is influenced by the light source striking the object.

True

True or False: On the Munsell Colorimetric System, black is more intense than white on the value scale.

True

True or False: Relative cone sensitivity functions show that each cone type responds to a wide range of wavelengths and there is some overlap at certain wavelengths.

True

True or False: A "negative" color has to be added in order to saturate two added colors to make a color match.

True Example: Blue + Green = 500nm, but it's desaturated, so we need to add Red to saturate it

What are metamers?

Two or more stimuli that have the same color but different wavelength composition

__________ provides a qualitative description of color matches and shows why 2 colors may not be sufficient to make color matches.

Newton's Circle

What does the purple locus on the CIE Chromaticity Diagram represent?

Non-spectral purples

Where are complementary colors located on a color circle?

On opposite sides of the center white dot

What is brightness?

Perceived intensity of a color

What is hue?

Perception most closely related to wavelength

How is spectral color obtained?

Prismatic decomposition of sunlight

What is Abney's Law?

Total luminance of light composed of several wavelengths is equal to the sum of luminances of its monochromatic components