SIMS%20247:%20Information%20Visualization%20and%20Presentation%20Marti%20Hearst

1
SIMS 247 Information Visualization and
PresentationMarti Hearst
Sept 19, 2005    
2
Color
Most of this segment taken from Colin Ware, Ch. 4
3
Terms

• Hue
• The differences in color that languages assign
  names to
• Saturation
• Sometimes called vividness, sometimes
  brightness
• Lightness
• A relative measure
• How much light appears to reflect from an object
  compared to what looks like white in a scene
  (Brewer)
• Also sometimes called value
• Other terms
• These are used inconsistently
• Intensity (often used to mean Saturation
  Lightness)
• Luminance (physically measured amount of
  reflected light)
• Chromaticity (hue without brightness)

4
Color Issues

• Complexity of color space
• 3-dimensional
• Computer vs. Print display
• There are many models and standards
• Color not critical for many visual tasks
• Doesnt help with determination of
• Layout of objects in space
• Motion of objects
• Shape of objects
• Color-blind people often go for years without
  knowing about their condition
• Color is essential for
• Breaking camouflage
• Recognizing distinctions
• Picking berries out from leaves
• Spoiled meat vs. good
• Aesthetics

5
CIE Color ModelCIE Commision Internationale
LEclairage
6
CIE Color Model Properties
7
CIE Color Model Properties
8
Small Color Patches More Difficult to Distinguish
9
Order of Appearance of Color Names across World
Cultures
10
Isolating Color Names within a Computer Display
11
Background Color Contrast
12
Some Color Fun Facts

• People agree strongly on what pure yellow is
• There may be two unique greens
• Brown is dark yellow, requires a reference white
  nearby

13
Colors for Labeling

• Ware recommends to take into account
• Distinctness
• Unique hues
• Contrast with background
• Color blindness
• Number
• Only a small number of codes can be rapidly
  perceived
• Field Size
• Small changes in color are difficult to perceive
• Conventions

14
Wares Recommended Colors for Labeling
Red, Green, Yellow, Blue, Black, White, Pink,
Cyan, Gray, Orange, Brown, Purple. The top six
colors are chosen because they are the unique
colors that mark the ends of the opponent color
axes. The entire set corresponds to the eleven
color names found to be the most common in a
cross-cultural study, plus cyan (Berlin and Kay)
15
More Color Use Guidelines

• From Cynthia Brewer reading
• Shes a cartographer, has a unique perspective
• Geocoordinates are already taken
• Four-way Guidelines
• Binary
• Qualitative
• Diverging
• Sequential
• Make combinations of these
• Seq-Seq, Seq-Qual, etc.
• Im not convinced these all work

16
Color Scheme Types (Brewer)
From http//www.personal.psu.edu/faculty/c/a/cab38
/ColorSch/Schemes.html
17
Binary Example
From http//www.personal.psu.edu/faculty/c/a/cab38
/ColorSch/Schemes.html
18
Sequential Examples
From http//www.personal.psu.edu/faculty/c/a/cab38
/ColorSch/Schemes.html
19
Sequential Example
From http//www.personal.psu.edu/faculty/c/a/cab38
/ColorSch/Schemes.html
20
Spectral SchemeNot suitable for sequential data
From http//www.personal.psu.edu/faculty/c/a/cab38
/ColorSch/Schemes.html
21
Qualitative Differences Example
From http//www.personal.psu.edu/faculty/c/a/cab38
/ColorSch/Schemes.html
22
Qualitative Color Schemes
From http//www.personal.psu.edu/faculty/c/a/cab38
/ColorSch/Schemes.html
23
Diverging Color Examples
From http//www.personal.psu.edu/faculty/c/a/cab38
/ColorSch/Schemes.html
24
Divering Color Scheme
From http//www.personal.psu.edu/faculty/c/a/cab38
/ColorSch/Schemes.html
25
Qualitative-Binary Example
From http//www.personal.psu.edu/faculty/c/a/cab38
/ColorSch/Schemes.html
26
Qualitative-Sequential Example
I suspect this is too much to keep track of.
From http//www.personal.psu.edu/faculty/c/a/cab38
/ColorSch/Schemes.html
27
Application to Class Projects

• Map of Immigration Routes
• http//www.sims.berkeley.edu/vijay/InfoViz/projec
  t/writeup/

28
Next Time

• Start Interaction Topics
• Turn in A1
• Learn about A2