CISC 110 Day 3

1
CISC 110Day 3

• Introduction to Computer Graphics

2
Outline

• Raster and Vector Graphics
• RGB Color Model
• Geometric Transformations
• Animation
• Tweening
• Masks

3
Vector Graphics

• Vector graphics is the use of geometrical
  primitives, such as points, lines, curves, and
  shapes or polygons, which are all based upon
  mathematical equations, to represent images in
  computer graphics.

4
Vector Graphics

• To draw a circle, a program needs to know the
  radius, the location of the center point, the
  line style and color, and fill style and color.
• More complex shapes can be created with Bézier
  curves.

5
Raster Graphics

• In computer graphics, a raster graphics image, or
  bitmap, is a generally rectangular grid of
  pixels, or points of color.

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Vector vs. Raster Graphics

• Raster images are based on pixels and thus scale
  with loss of clarity, while vector-based images
  can be scaled indefinitely without degrading.

7
RGB Color Model

• The RGB color model is an additive color model in
  which red, green, and blue light are added
  together to produce a wide range of colors.

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RGB Color Model

• An RGB image, along with its separate R, G and B
  components

9
Numerical Representation

• A color in the RGB color model is described by
  indicating how much of each of the red, green,
  and blue is included. The color is expressed as
  an RGB triplet (r,g,b), each component of which
  can vary from zero (no light) to a defined
  maximum value (usually 255).

10
Geometric Transformations

• A translation moves every point of a figure or a
  space by the same amount in a given direction.
• A rotation is a progressive radial orientation to
  a common point. That common point lay within the
  axis of that motion.

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Animation

• Animation is the rapid display of a sequence of
  images of 2-D or 3-D artwork or model positions
  in order to create an illusion of movement.

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Traditional Cell Animation

• Transparent cels, each with a different character
  drawn on them, and an opaque background are
  photographed together to form the composite image.

13
Tweening

• Inbetweening or tweening is the process of
  generating intermediate frames between two images
  (key frames) to give the appearance that the
  first image evolves smoothly into the second
  image.

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Motion, Shape Color Tweening
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Masks

• A mask provides a hole through which underlying
  layers show, so that you can limit the area of
  the layers that is visible.