Metamerism Questions and Answers

Answer: C

The first two are correct and locate the cause. The third confuses a difference with a metameric relationship, which are quite separate things. A difference need not be metameric at all. The two ideas are quite separate.

Answer: D

Correct answer: the illuminants used as reference and as test

The index measures the degradation of a match between a specific pair of illuminants, so a figure quoted without naming them means nothing: the same pair of samples may score well against one test illuminant and badly against another. The observer and the correction method must be stated for the same reason.

Answer: A

Correct answer: the country in which the sample was produced

The index depends on the reference illuminant, the test illuminant, the standard observer and the correction method applied, and all four must be quoted for the number to be reproducible. Where the sample was made has no bearing on the calculation, whatever its commercial interest.

Answer: B

Deviate observer functions representing the population spread are used. The resulting index measures how much observers are likely to disagree. Deviate functions represent the population spread. The standard observer alone shows no variation.

Answer: C

Correct answer: Both A and R are true, and R is the correct explanation of A

Both are true and the reason gives the mechanism. Observer metamerism is the variation of a match between real people with different colour matching functions, and the standard observer is a single averaged set representing no spread at all. Assessing it therefore requires a set of deviate observer functions, which is what the standard deviate observer provides.

Answer: D

Switching between them reveals a pair that separates under one condition. A single illuminant conceals exactly what the test is meant to find. Switching between them exposes the separation. A single illuminant hides the failure.

Answer: A

Correct answer: 2 - 4 - 1 - 3

Measurement comes first because everything after it is computation on the same spectral data. The colour difference under the reference establishes whether the pair matches at all; the differences under the test illuminants establish how that match holds up; and both are then reported together, since neither figure means much without the other.

Answer: B

Correct answer: crossovers reveal metamerism immediately to the eye

Two curves that cross several times while enclosing roughly equal areas are the visual signature of a metameric pair, and it is apparent at a glance in a way no single number conveys. The plot shows where the difference lies in wavelength, which is what suggests which colourant is responsible.

Answer: C

Such a pair will match under any illuminant and for any observer. It is the most robust kind of match obtainable. No change of condition can break it. It is the most durable match available. Identical spectra are what make it so.

Answer: D

Robustness rather than the size of the difference is the advantage. The cost is usually higher because the same colourants are required. Robustness rather than closeness is the gain. The same colourants are usually required.