The Science of Color Quiz | Physics

Quiz Answer Key and Fun Facts

1. "Color" is the name given to the chromatic components of appearance. Which is NOT a chromatic attribute?

Answer: gloss

The chromatic attributes of appearance are hue (used to distinguish between colors), value (lightness), and chroma (departure from neutral, also known as saturation).

The geometric attributes of appearance include gloss, texture, shape, surround, and viewing angle.

2. Color can be defined as what type of response?

Answer: psychophysical

Color is the perception or subjective response of an individual observer to the physical stimulus of visible light. Color, therefore, has both a subjective and objective component and does not have a direct correspondence with spectral energy.

3. Despite light sources being very important to the perception of color, objects that we are familiar with do not seem to significantly vary with changes in lighting or conditions. For example, your clothes appear to be the same color as you move from your house/apartment (incandescent light) to outside (daylight) to the supermarket (fluorescent light). What is this phenomenon called?

Answer: constancy

The chameleon effect and complementary afterimage are both optical illusions that take advantage of other ways our brain interprets color information.

4. An "illuminant" is the term used to describe the light energy that hits an object. What is used to refer to the color of illuminants?

Answer: temperature

Color temperature is the temperature (in Kelvin) at which a black body radiator will match the light source, and is related to Planck's Law.

Note that all light sources are illuminants, but not all illuminants are light sources, since illuminants can be theoretical or use mixed light sources.

5. When two objects with different reflectance spectra appear to have the same color under certain illuminants and not others, it is called:

Answer: metamerism

Metamerism can be predicted. When the reflectance spectra of two objects cross three or more times, the objects are metamers.

Unfortunately, it is not easy to predict exactly under which illuminants the two objects will match or not.

6. Instrumental color analysis relies on "standard observer" models to match the subjective response of color to spectral data. Which of these models was established first?

Answer: 2� Observer

In 1931, studies established the 2� Observer, which restricted the visual field of the subjects to the fovea, the area of the retina with the highest concentration of cone cells. Later, the 10� Observer, which used a larger viewing angle, was established in 1964.

7. Color data is reported using coordinates in a "color space". Which of these color spaces is not like the others?

Answer: Munsell

The Munsell color space was developed by Albert H. Munsell in 1905 (later updated in 1943), and uses hue, value, and chroma to distinguish colors. There are 5 primary and 5 intermediate hues, with 100 arbitrary steps of equal visual change in hue.

L*a*b* (1976) uses lightness, red/green, and blue/yellow axes to define the color space in a Cartesian (rectangluar) coordinate system. LCh uses the same color space but reports data using lightness, chroma, and hue as polar coordinates. Richard S. Hunter's system was created in 1942 and is very similar to L*a*b*, but uses different equations.

8. The "viewing geometry" is the term used to describe the angles between the light source, object, and observer (or detector). What viewing geometry is NOT used in color analysis?

Answer: C6

A viewing geometry of 0/45 places the light source directly above the object at 0�, and the observer/detector at a viewing angle of 45�. This is the set up in most light boxes.

A viewing geometry of 45/0 switches those positions, placing the observer/detector directly above the object ant the light source at 45�.

D8 denotes a spherical geometry where the detector is placed at 8� to the object using an illuminated sphere.

9. What light source is used for most color analysis instruments?

Answer: xenon

Xenon gives a wide illuminant spectrum that is used to derive other light sources, such as CWF (cool white fluorescent) or D65 (north sky daylight).

Tungsten is used for visible spectroscopy and deuterium is used for ultraviolet spectroscopy. Neon is used for brightly colored signs.

10. When performing an instrumental analysis of color, when should you include the specular component?

Answer: when reporting "true" color measurements

Under most circumstances, the Specular Component is Excluded (SCE), as this is equivalent to appearance and what a visual observer would see.

Generating data with the Specular Component Included (SCI) is only possible with spherical optics, and reports the "true" color, independent of gloss, texture, and other surface features that a visual observer cannot ignore.

Source: Author jcpetersen

This quiz was reviewed by FunTrivia editor crisw before going online.
Any errors found in FunTrivia content are routinely corrected through our feedback system.

The Science of Color Trivia Quiz

Color is something most people are very familiar with, but the scientific discussion and evaluation of color may not be as common.

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