Metamerism Questions and Answers

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. Vegetation reflects strongly in the near infrared, and a pigment matching it in the visible need not do so beyond 700 nm. A material indistinguishable from foliage to the eye can therefore stand out sharply under an infrared imager, which is why modern camouflage specifications extend well past the visible band.

Answer: D

A pair matching visually may differ greatly outside the visible band. Military and security applications routinely specify performance across a wider range. Infrared behaviour is entirely unconstrained by a visual match.

Answer: A

Nothing in a visual match constrains the reflectance outside the visible. Applications using infrared detection must specify that band separately. A visual match says nothing about the infrared. That band must be specified separately.

Answer: B

More degrees of freedom allow the curve shape to be fitted more closely. Cost and complexity rise correspondingly with each colourant added. Degrees of freedom improve the achievable fit. Cost rises with each colourant added.

Answer: C

Both are true and the reason gives the mechanism, and cost rises with each addition. Three colourants can match the integrals but rarely the whole curve. Matching a curve needs more freedom than matching three numbers.

Answer: D

Correct answer: 1 and 2 only

Statements 1 and 2 are correct: three colourants give three degrees of freedom, enough to hit three tristimulus values, and adding a fourth or fifth allows the curve itself to be approximated more closely. Statement 3 confuses the two - matching three numbers is a far weaker condition than matching a curve at every wavelength, and three colourants generally leave a metameric result.

Answer: A

Correct answer: a match must be verified under the conditions of use

Everything else in the subject follows from this. A match is a match under stated conditions, so if the goods will be seen under shop lighting and daylight, the match must be checked under both. No instrument, no index and no tolerance substitutes for assessing under the light the customer will actually use.

Answer: B

Correct answer: the boundary of colours achievable by any real reflecting surface

The optimal colour limits, associated with Rosch and with MacAdam, bound what a reflecting surface can achieve at a given lightness, and they are reached by theoretical reflectances that switch between zero and one at particular wavelengths. They lie well inside the spectrum locus, which is bounded by monochromatic light that no reflecting surface can produce.

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. Near the optimal colour boundary only reflectance curves close to the ideal block shape reach the chromaticity at all, so there is very little freedom left for two different curves to arrive at the same point. Metamerism needs that freedom, and near the limits it does not exist.

Answer: D

Correct answer: 1 and 2 only

Statements 1 and 2 are correct and are two halves of the same fact: a near neutral can be produced by a great many spectral curves, so metameric pairs arise easily there, while a highly saturated colour requires a curve of a particular shape and admits far fewer alternatives. Statement 3 contradicts both - the likelihood varies strongly with position in the colour solid.