Color Properties - Hue & Saturation

Question 1

What are three modes of color?

Which mode is the most common, the sky would be an example of which one, which has to do with light distribution?

Answer 1

• Surface color (object absorbs wavelength, most common)
• Aperature color (perceived color not associated with object)
• Direct Illumination (due to light distribution color onto an object)

Question 2

Which Psychological property is NOT correctly matched up with it’s Physical property?

A. Hue - Wavelength
B. Saturation - Colormetric Purity
C. Brightness - Luminance
D. Chromaticiness - Chromatic Purity
E. All are correctly matched

Answer 2

D. Chromaticiness - Chromatic Purity

Should be matched up with Chromaticity

Question 3

Describe Hue

(What it is, what is a descrimination ellipse used for, Can it be used to accurately determine color deficiency? Physical measured by what?

Answer 3

• Perception of color
• Descrimination ellipse used to psychologically measure hue
• Cannot be used to accurately determine color deficiency
• Uses wavelength to measure color

Question 4

Describe saturation

What it is, what happens, when you add white, what’s Physically measured and two examples of how its measured

Answer 4

• Measure concentration/dilution of color
• Diluted by adding white
• Physically measured by Colorimetric Purity
• Two examples: CIE chromaticity diagram and Excitation Purity

Question 5

What wavelengths do Normal trichromats look saturated?

A. 490 nm
B. 492 nm
C. 498 nm
D. 570 nm
E. 580 nm

Answer 5

D. 570 nm

Question 6

What wavelengths appears “white” to a Duetan?

A. 490 nm
B. 492 nm
C. 498 nm
D. 570 nm
E. 580 nm

Answer 6

C. 498 nm

Question 7

What wavelengths appears “white” to a Protan?

A. 490 nm
B. 492 nm
C. 498 nm
D. 570 nm
E. 580 nm

Answer 7

B. 492 nm

Question 8

Define “spectral light” as it relates to saturation discrimination

Answer 8

• It is the amount of color wavelength that is added to white until it can be discriminated that it is not white anymore

Question 9

What is the formula for colorimetric purity (saturation discrimination)

Answer 9

• Lwavelength / (Lwavelength + Lwhite)

Question 10

What is the formula for Excitation purity on the CIE Chromaticity diagram and what does each variable mean (a, b)?

Also, what does a Excitation Purity of 1 and O mean?

Answer 10

• a/(a+b)
• a = distance to reference white
• b = distance to spectral locus

1 - monochromatic lights
0 - Pastels, Reference White

Question 11

Define Planckian locus on a CIE Chromaticity Diagram

Answer 11

• The area where white is represented by several points, based on different standard illuminants

Question 12

Non-spectral purple on a CIE Chromaticity Diagram is produced by a single wavelength. TRUE/FALSE

Answer 12

• FALSE