Colour Theory and Application

1
Colour Theory and Application
B.Sc. (Hons) Multimedia Computing
Media Technologies
2
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
Media Technologies
3
Colour Temperature
4
The Colour Wheel
5
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.

6
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
7
Additive Synthesis
B.Sc. (Hons) Multimedia Computing
Media Technologies
8
Colour ModelsRGB

• 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
9
Subtractive Synthesis
B.Sc. (Hons) Multimedia Computing
Media Technologies
10
Subtractive Synthesis
B.Sc. (Hons) Multimedia Computing
Media Technologies
11
Colour ModelsCMYK

• 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
12
CMYK Subtractive
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.
B.Sc. (Hons) Multimedia Computing
Media Technologies
13
Colour Models RGB CMYK
B.Sc. (Hons) Multimedia Computing
Media Technologies
14
B.Sc. (Hons) Multimedia Computing
Media Technologies