RGB Color System

1
RGB Color System

• In the RGB color system, each color is defined by
  a triple (r,g,b) where each of r, g, b is an
  integer between 0 and 255.
• RGB yields 2563 (or 16,777,216) distinct colors.
• HTML codes converts these numbers into
  hexadecimal (for example, at this page).

2
RGB Color Space

• Go to http//www.tech.purdue.edu/cg/facstaff/jlmoh
  ler/dcm.html and click on the RGB tab.
• Determine what colors are generated when r,g, and
  b can only be 0 or 255.
• Find paths from black to white that
• never use red
• pass through cyan, but not blue or green
• never passes through red, blue, green, cyan,
  magenta, or yellow

3
Hue-Saturation Systems

• A number of different systems use
• hue (to fix a point on the color spectrum),
• saturation (to determine the intensity of color)
• and some measure of brightness, luminence, etc.
• Go to the HSB/HSV tab and see how movement in
  this space affects color.

4
Image Processing

• The craft of converting an image into digital
  form (in this case, picking a numerical grayscale
  value for each portion of the photograph)

Leon Harmon, Bell Labs
5
Practice

• Take this image and use Paint to approximate the
  image using color matching with the given grid.

6
Approximating images

• Squares in this image have been replaced with
  square of constant color.
• How do we make the color choice?
• One suggestion average your r, g, and b values.

7
Examples - Photomosaics

• A photograph made of 3000 photographs
• Requires mathematical algorithms to not only
  match color, but shape

8
Examples - Dali

• Lincoln in Dalivision (1977)