Colour Theory and Application

B.Sc. (Hons) Multimedia Computing

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Describing Colour

• Words we might use when naming and describing colours:

• ‘shade, hue, warm, tone, bright, dim, pale, intense, vivid, rich, saturated, cold, strong, wishy-washy, glowing, colour, flat, weak, muddy, soft, vibrant, luminance, bold, tint’

• Very subjective - influenced by perception and characteristics of illuminating light source.

B.Sc. (Hons) Multimedia Computing

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Colour Temperature

The Colour Wheel

Hue, Saturation, Value (HSV)

The HSV model is based on the following concepts

• Hue - this is what most people would refer to as the colour or shade. Red, yellow, green and blue are hues.

• Saturation - this is a value that represents where the colour is on a scale from achromatic white to the pure hue.

• Value - is the attribute, sometimes referred to as brightness, which determines how intense the colour is on a a scale from black to the pure hue.

Colour Models

• Additive Synthesis - Start with no light. Add red green and blue light to make white and complementary colours

• Subtractive Synthesis start with white light. Subtract red green and blue light to achieve complementary colours and black

B.Sc. (Hons) Multimedia Computing

Media Technologies

B.Sc. (Hons) Multimedia Computing

Media Technologies

Additive Synthesis

Colour Models:RGB

• Display devices generally use a color model called RGB.

• Stands for Red-Green-Blue• Based on the additive synthesis model• RBG colour value specified in three bytes

B.Sc. (Hons) Multimedia Computing

Media Technologies

Subtractive Synthesis

B.Sc. (Hons) Multimedia Computing

Media Technologies

B.Sc. (Hons) Multimedia Computing

Media Technologies

Subtractive Synthesis

Colour Models:CMYK

• Cyan-Magenta-Yellow-Black, and pronounced as separate letters. CMYK

• Based on the subtractive synthesis model• CMYK is a colour model in which all colors are

described as a mixture of these four process colours.

• CMYK is the standard colour model used in offset printing for full-colour documents. Because such printing uses inks of these four basic colours, it is often called four-colour printing.

B.Sc. (Hons) Multimedia Computing

Media Technologies

CMYK Subtractive

B.Sc. (Hons) Multimedia Computing

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Subtractive color: Illuminate objects that contain dyes or pigments that remove portions of the visible spectrum.The objects may either transmit light (transparencies) or reflect light (paper, for example).The subtractive primaries are C, M and Y. Cyan absorbs red; hence C is sometimes called "minus red" (-R). Similarly, M is -G and Y is -B.

Colour Models: RGB & CMYK

B.Sc. (Hons) Multimedia Computing

Media Technologies

B.Sc. (Hons) Multimedia Computing

Media Technologies