Additive and Subtractive Mixing Questions and Answers

Answer: C

Correct answer: a specially mixed ink printed in a single impression

A spot colour is mixed to the required shade before printing and laid down in one pass, so it needs no registration and no halftone build. That is why it can reach colours outside the process gamut and why it reproduces consistently - and why it costs an extra plate and press unit.

Answer: D

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. A process build depends on three or four inks landing in register at the right densities, and every one of those varies through a run and between presses. A single mixed ink is matched once and laid down in one impression, so the colour a company is known by comes out the same everywhere.

Answer: A

Correct answer: on the straight line joining them in the chromaticity diagram

Because tristimulus values add, the mixture is a weighted average of its components, and a weighted average of two points lies on the segment between them. The position along the line depends on the relative luminances. This is why the gamut of three primaries is the triangle they define.

Answer: B

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. The tristimulus values of the mixture are the sums of the components’, and chromaticity coordinates are those values normalised - so the mixture is a convex combination of the two points and must lie between them. Linearity is exactly what makes the path straight.

Answer: C

Correct answer: False

Colourant mixing is subtractive and multiplicative, so the mixture’s chromaticity generally follows a curved path that bows towards the neutral point. This is why mixing two saturated paints gives something duller than either, and it is the fundamental difference from the additive case, where the path is straight.

Answer: D

Any colour inside the triangle can be matched by some combination of the three. Colours outside it cannot be reached without a negative amount. The triangle bounds what three primaries can do. Outside it requires a negative amount.

Answer: A

A fourth primary extends the polygon and adds area to the gamut. Multi-primary displays exploit exactly this at the cost of greater complexity. A polygon of more vertices encloses more area. Returns diminish with each primary added.

Answer: B

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. Three primaries define a triangle in the chromaticity diagram; adding a fourth or fifth primary outside that triangle turns it into a polygon enclosing more area. Since the spectrum locus is convex and no triangle can cover it, more vertices is the only way to approach it.

Answer: C

They convert ultraviolet into visible blue, which no absorbing colourant can do. This lets a substrate appear brighter than a perfectly white diffuser would. No absorbing colourant can add light. Fluorescence supplies what absorption cannot.

Answer: D

The first two are correct and describe fluorescence. The third describes a blueing agent instead, which is a quite different and less effective approach. Blueing removes light rather than adding it. The two achieve similar ends by opposite means.