CS 101 - 10/4/11

Picture Manipulation: Chapter 4, 5, 6

A picture is a matrix (2D array) of pixels

A pixel is a PIcture ELement that contains:

    X and Y coordinate of the location in the picture
    The RED amount,
    The GREEN amount and
    The BLUE amount of color at the position

Each color will be represented by a value from
    0  to 255.   

      0  => no amount of that color
      255 => maximum amount of that color 

     RGB (0, 255, 127)  = color between Green and Cyan
     RGB (0,0,0)         => Black
     RGB (255, 255, 255) => White
     RGB (255, 0, 0)     => Red
     RGB (0,255,0)       => Green
     RGB (255, 255, 0)   => Yellow

   The value from 0 to 255 are represented by an
     8 bit binary number (or 1 byte)

   3 MegaByte image => about 1 million pixels

    1024 x 1024 x 3 = 3 MegaBytes


  For Loop: alternative to the while loop

  xPos = 0;
  While ( xPos < width )
  {
     // do something


     xPos = xPos + 1;
  }

  A while loop has 3 parts:
     initialization:  xPos = 0
     condition:       xPos < width
     increment:       xPos = xPos + 1

   The 4th part is the Body, which does the intended
     task

  A for loop attempts to simplify the while by
    combining the initialization, condition and
    increment onto a single statement.

  for ( xPos = 0 ;  xPos < width ; xpos = xPos + 1 )
  {
      // do something

  }