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How does colour theory guide the choice of colours in a graphic, and how do RGB and CMYK differ?

Colour theory: the colour wheel (primary, secondary and tertiary colours), harmonies (complementary, analogous, monochromatic), warm and cool colours and the psychology/associations of colour, and the RGB versus CMYK colour models.

An SQA Higher Graphic Communication answer on colour theory, covering the colour wheel (primary, secondary, tertiary), colour harmonies, warm and cool colours, colour psychology, and the difference between the RGB and CMYK colour models.

Generated by Claude Opus 4.812 min answer

Reviewed by: AI editorial process; not yet individually human-reviewed

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  1. What this key area is asking
  2. The colour wheel
  3. Colour harmonies
  4. Warm and cool colours
  5. Colour psychology and associations
  6. RGB versus CMYK
  7. Worked example
  8. Examples in context
  9. Try this

What this key area is asking

The SQA wants you to apply colour theory: the colour wheel (primary, secondary, tertiary), harmonies (complementary, analogous, monochromatic), warm and cool colours, the psychology/associations of colour, and the RGB versus CMYK colour models. Colour is one of the most powerful design elements, so choosing it deliberately matters.

The colour wheel

Colour harmonies

Warm and cool colours

Colour psychology and associations

RGB versus CMYK

Worked example

Examples in context

Brand identities live and die on colour: fast-food brands lean on warm red and yellow (energy, appetite, attention), banks on blue (trust), eco brands on green. The RGB/CMYK split is a daily reality for any designer who produces both a website and printed material from the same artwork, and it explains the familiar disappointment of a vivid screen colour printing duller.

Try this

Q1. State the three primary colours on the colour wheel. [1 mark]

  • Cue. Red, yellow and blue.

Q2. State which colour model is used for screens and whether it is additive or subtractive. [2 marks]

  • Cue. RGB; it is additive (it adds red, green and blue light).

Q3. State the harmony made from two colours opposite each other on the wheel. [1 mark]

  • Cue. Complementary.

Exam-style practice questions

Practice questions written in the style of SQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.

SQA Higher (style)4 marksExplain the difference between the RGB and CMYK colour models, stating when each is used and why a screen design can look different when printed.
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RGB (red, green, blue) is an additive model used for anything that emits light, such as computer screens, phones and TVs. Colours are made by adding red, green and blue light; all three at full give white, and none gives black. It has a wide range (gamut) of bright colours.

CMYK (cyan, magenta, yellow, key/black) is a subtractive model used for printing with inks. Inks absorb (subtract) light from white paper; combining cyan, magenta and yellow gives a dark colour, and black (K) is added for true blacks and to save ink. Its gamut is smaller than RGB, especially for bright, saturated colours.

A screen design can look different when printed because some bright RGB colours fall outside the CMYK gamut, so they cannot be reproduced exactly and are shifted to the nearest printable colour. This is why designers preview or convert to CMYK and use proofs before printing.

Markers reward: RGB = additive light for screens (wide gamut), CMYK = subtractive inks for print (smaller gamut, black added), and out-of-gamut RGB colours cannot print exactly, causing a shift.

SQA Higher (style)3 marksDescribe a complementary and an analogous colour harmony, and explain how colour psychology might guide a colour choice for a brand.
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A complementary harmony uses two colours opposite each other on the colour wheel (for example blue and orange). They create strong contrast and make each other look more vivid, so they are eye-catching but can clash if overused.

An analogous harmony uses colours next to each other on the wheel (for example blue, blue-green and green). They are naturally harmonious and calm, because they share an underlying hue, but offer less contrast.

Colour psychology means colours carry associations: blue suggests trust, calm and professionalism; green suggests nature, health and growth; red suggests energy, urgency or warning; yellow suggests optimism and attention. A brand chooses colours whose associations match its message, for example green for an eco or health brand to suggest natural and healthy.

Markers reward: complementary = opposite on the wheel (high contrast), analogous = adjacent (harmonious), and a sensible colour-psychology link guiding a brand choice.

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