Colour Flashcards
Why is colour important?
- Clarifies
- Simplifies
- Attracts Attention
- Leads the Eye
- Enhances Perceptibility
Color Brewer
- Website resource for colour choices
- Powerful cartography tool
- Created by past Cartography student
What are key things to understand about colour?
- Visual reaction to colour
- Visual sensation of colour
- How colours interact with each other
Figure Ground
- Ability to separate elements based upon contrast
- Employed to discern difference between back ground and foreground
- Not just about lines, but how it is shaded
- Famous example: Rubin’s Vase
Rubin’s Vase
- Classic example of figure ground optical illusion
- Is it a vase, or two faces
- Shows how perception can play a role in cartography
Is the flag of Canada an optical illusion?
- Not really but it could almost look like two people fighting
How do we see colour?
- Receptors in the eye that are stimulated by portion of electromagnetic spectrum
- We distinguish 7 predominant colours (hues)
- ROYGBIV
Electromagnetic spectrum
- Entire spectrum appears as white light
- When refracted through prism actually shows the various wavelengths as the 7 predominant colours ROYGBIV
- Humans see 400-700nm
What portion of the electromagnetic spectrum do humans see?
- 400-700nm
- ROYGBIV
- Some people don’t see all and are colour blind
How do lightbulbs affect colour?
- Light bulbs change colour
- Full spectrum lightbulbs are more comfortable because they produce natural light
ROYGBIV acronym
Ring Out Your Great Bells In Victory
What are the 3 dimensions of colour?
- Hue
- Chroma
- Value
Hue
- Colours, ROYGBIV
- Infinite number of colours
Chroma
- Intensity, not brightness
- Saturation, purity
- Compare colour to neutral grey, with addition of pigment, will appear less and less grey
- White, Grey, and black are achromatic
Which colours are achromatic?
White, Grey, and black are achromatic
Value
- Lightness or Brightness of hue
- Measured w/ instruments
- Conceptually easy, difficult in practice
- Subjective for humans, but can measure w/ spectral responses
- Computer usually manages value
What are the 2 key ways of classifying colour?
- Additive Light Mixing
- Subtractive Pigment Mixing
Additive Light Mixing
- RGB
- Colours added to produce new colours
- White is all colours, black is no colours
What is Additive Light Mixing used for?
- For projecting
- RGB
Subtractive Pigment Mixing
- CMYK
- K is black
What is Subtractive Pigment Mixing used for?
- For printing
- CMYK
What does CMYK stand for
Cyan, Magenta, Yellow, K is black
What is the main difference between RGB and CMYK?
- Additive RGB is how computers display and project colour
- Subtractive CMYK is how printers will display colour
Why does CMYK need the K?
Because CMY cannot mix together to create a good enough black on their own
What are examples of colour classification systems and years established?
- Munsell (1915)
- Ostwald (1917)
- CIE (1931)
- RGB
Explain the Munsell colour classification system
- 1915
- 10 major hues
- 10 value levels
- 12 chroma levels
- 1500 total colour specs
- Subtractive, Good for print not digital
- Used a physical 3D model to find colours
Describe the Munsell 3D model to find colours
- Wheel of 10 hues
- Vertical center representing 10 value levels
- Horizontal from wheel represents 12 chroma levels for each hue on the wheel
Explain the Ostwald colour classification system
- 1917
- 24 hues on hue circle
- Adds different amount of white/black on vertical
- Represented by C (colour), W (White), and B (Black)
- Simple, precise
- Subtractive pigments
What does 40, 10, 50 represent in the Ostwald colour system?
40% colour, 10% White, 50% Black
Who was Ostwald and how did he develop his colour system?
- Physicist and Nobel Prize winner
- Reflectance Curves
Explain the CIE colour classification system
- Additive digital system
- Reaction of light/energy hitting things
- Standard illumination source (tungsten lamp, noon sunlight, average sunlight on overcast day)
- Standard observer (average human response)
- Standard primaries (Red, green, blue)
What does CIE stand for?
Commission International De L’Eclairage
What are the standard primaries in the CIE?
- Red, x
- Green, y
- Blue, z
- Set up on a cube
Explain the RGB colour classification system
- 16 million possible colours
- Additive, digital
- RGB is XYZ with values between 0-255 each (256 #’s)
What does 0,0,0 represent in RGB?
Black
What does 255,255,255 represent in RGB?
White
What does 255,0,0 represent in RGB?
Red
What does 255,0,255 represent in RGB?
Magenta
- all red, all blue
What are some considerations to take into account when choosing colours and colour combinations?
- Cultural Controls
- Convention
- Depth Perception
- Value
- Data Levels
What are the perceptual primaries and what are the other colours?
Primaries: blue, red, green, yellow, brown, black, white
- Other colours appear as mixtures (pink, orange, etc.)
What does red represent culturally?
- Danger, Stop
What does yellow represent culturally?
- Sacred in East
- Indecision in West
What are colours associated with funerals?
- White in India
- Black in West
What colours are best for different age groups?
- High saturation chroma for children
- Softer tones for older people
What is an example of a cultural colour that might be best to avoid?
- Blue = boys
- Pink = girls
What are some cartographic conventions for colour?
- Blue = Water/cool
- Red = Warmth/ towns/ danger- Green = Vegetation/ lowlands/ forests
- Yellow = Dryness/lack of veg
- Brown = Contours/ landforms
What do blue and red represent on a geology map (cartographic conventions)
Blue = Carbonate (water formed, cool) Red = Igneous (volcanic, hot)
How does depth perception affect colour (relates to physics)?
- Light rays refract inversely to wavelength
- Blue focus in front of retina and red focus behind retina
- Therefore red appears nearer than blue in front of the eye fractionally
- Red appears more important
What is value?
- Lightness or darkness
- Humans are not very sensitive to value
- Value appears inconsistent depending on interference by surrounding colours
- Can interfere with depth perception
What is one way to help choose colour schemes and help with figure ground?
- Use a colour wheel organized in chromatic order
- Choose complimentary colour opposite on the wheel
Data levels with colour
- Nominal: colour has no meaning
- Ordinal/ Interval/ Ratio: colour has meaning
What are some key guidelines for choosing colours on maps?
- Avoid too many colours
- Avoid loud colours
- Avoid clashing colours
- Keep It Simple (KIS)
- Design map for audience, not yourself
