# Introduction to Shape and Color

## Shape

### 2-D Plane Geometry

• Line 6.5.2
• Angle 6.10
• Vertex
• Reference angle
• Terminating side
• Circles and arcs 6.5.4
• Center
• Diameter
• Circumference
• Chord
• 3 Point
• Polygons 6.12.1
• Regular polygons
• Rectangles
• Triangles
• Irregular polygons
• Geometric operations and terms 6.5
• Circumscribe
• Inscribe
• Bisect
• Tangent
• Parallel
• Midpoint
• Endpoint
• Intersect

### Type 4.9

• Font
• Style
• Size
• Capitalization

## Color Principles

### Definition of color 21.3.6

• Perceptual response to visible light wave energy
• The totality of all wavelengths reaching the eye
• 400 nm to 700 nm
• Perceptual dimensions - HSV model
• Hue
• What we normally think of as 'color'
• Related to wavelength
• Saturation
• Ratio of dominant hue (wavelength) to others
• Gray equals no hue
• Value (lightness)
• Total intensity (luminance) of light
• Can be represented at a HSV Hexacone

### Uses for color 20.4.3

• Representing energy not visible to the eye
• grayscale on an X-ray
• hue coding on a infrared satellite image
• Reprenting conceptual data dimensions
• Mapping dimensions of color to ranges of data values
• Assigning specific colors to discrete values
• Color coding lines on a graph
• Representing ideas or concepts
• e.g., red for hot, blue for cold
• Representing common uses for color
• e.g., green for go or start

### Computer hardware - RGB model 21.3.6

• Defined by mixture of three additive primaries
• Red, Green, Blue
• Represents mixture of illuminated light
• Can be represented by a RGB cube
• Used in definition of color in computer graphics
• Subtractive primaries
• CYM - Cyan, Yellow, and Magenta
• Each paired with additive primary
• Represents mixture of reflected light
• Used in pigment definition along with black (CYMK)
• Using in printing - Offest, inkjet, etc.
• Projection of RGB cube along lightness axis
• Gives hue hexagon
• Additive and subtractive primaries opposite each other

### Implementation of color 21.3.6

• Define number of available colors
• Infinite number in real world
• Limited number on paper or computer monitor
• Computer graphics based on number of colors for each primary color
• 1-bit: Two total colors
• Usually black and white
• 8-bit: 256 total colors
• Can be gray (lightness) or color scale
• 24 -bit: 16+ million colors
• 8 bits per RGB primary
• Each primary takes a value from 0 to 255
• Color assignment
• Each pixel (on screen) can be assigned a value
• Each value is assigned a look-up color
• Assignments held in look-up table (LUT)
• General rules of thumb
• Color is not good for perception of exact numeric values
• Lightness and saturation can be used for ordinal scales
• Lightness (grayscales) most common
• Hue can be used for nominal scales
• Only used in ordinal scales with supplied legend

## Other Descriptive Properties

### Dimensionality

• 0-D (dot)
• 1-D (line)
• 2-D (area)
• 3-D (volume)
• 4-D (volume plus time)

### Detail

• Outline
• Surface detail
• Texture
• Pattern

### Level of Abstraction

• Symbolic (abstract)
• Iconic (stylized realism)
• Realistic

### Linear Elements

• Width
• Length
• Density (darkness)
• Curvature