Kubelka Munk theory relates
Answer: A
The K over S function is approximately additive in colourant concentration. This is what makes computer colour matching arithmetically tractable. Concentration enters approximately linearly. That linearity is what makes matching feasible.
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Assertion (A): Kubelka Munk theory is central to computer colour matching.
Reason (R): The K over S function is approximately linear in colourant concentration.
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. \( K/S = (1-R)^2/2R \) is very nearly proportional to concentration and additive across colourants, so a target curve can be decomposed into contributions and solved for the concentrations. Without that near-linearity, recipe prediction would be an intractable search rather than a calculation.
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Consider the following statements about Kubelka Munk theory.
1. K over S is approximately additive across colourants.
2. Reflectance itself is not additive in concentration.
3. The theory applies without modification to transparent media.
Answer: C
The first two are correct and are the basis of recipe prediction. The third is not so, since the two constant theory assumes an opaque scattering medium. Transparent media need a different treatment. Two constant theory assumes scattering.
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A display produces colour by
Answer: D
The three elements are too small to resolve individually at normal viewing distance. Their light adds at the retina to give the perceived colour. Elements are unresolvable at normal distance. Their light adds at the retina instead.
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Spatial additive mixing occurs when
Answer: A
Correct answer: small coloured elements are too fine to resolve individually
When the elements fall below the eye’s resolving power their light is integrated on the retina and adds, so the effect is additive even though the elements are printed inks. Halftone printing, a display’s subpixels and pointillist painting all work this way, and all three revert to visible separate colours at close range.
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Match each form of additive mixing with an example.
List I
A. Superposition
B. Spatial
C. Temporal
D. Binocular
List II
1. a spinning disc of coloured sectors
2. two spotlights overlapping on a wall
3. different colours presented to each eye
4. a display with unresolvably small pixels
Answer: B
All four combine lights rather than removing wavelengths. The first three are used routinely in colour reproduction technology. All four combine lights rather than removing them. Three of them are used in reproduction technology.
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A Maxwell disc demonstrates
Answer: C
Above the flicker fusion frequency the sectors merge into a single colour. The result is the additive average weighted by the area of each sector. Above flicker fusion the sectors merge entirely. Area weighting gives the resulting colour.
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Assertion (A): A Maxwell disc gives an additive result although it is covered in pigments.
Reason (R): The eye integrates the light reflected in succession rather than mixing the pigments themselves.
Answer: D
Both are true and the reason gives the mechanism, and the pigments never touch one another. It is a neat demonstration that the process rather than the material defines the result. The pigments themselves never touch one another.
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State whether the following is true or false.
Halftone printing produces its intermediate tones by additive mixing.
Answer: A
Correct answer: True
The intermediate tones come from varying the area covered by dots too small to resolve, and their light adds in the eye - spatial additive mixing. The process is not purely one thing or the other: where dots of different inks overlap on the paper, that overlap is subtractive.
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Consider the following statements about halftone printing.
1. Adjacent dots mix additively in the eye of the viewer.
2. Overlapping dots mix subtractively where they coincide.
3. Halftone printing is a purely subtractive process throughout.
Answer: B
Correct answer: 1 and 2 only
Statements 1 and 2 together describe what actually happens: adjacent dots add in the eye, overlapping dots subtract on the paper. Statement 3 misses the first of those. It is the combination that the Neugebauer equations model, by treating the sheet as a mixture of the sixteen possible overlap primaries.
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