CS 111 - 2/23/17

The human eye does not perceive the colors of red, green 
   and blue as having the same luminence (brightness)

   A black&White/gray-scale picture should reflect the 
     luminance of the original 

   This is noted on pp103, 104 in the text.

   According to the research noted in the book.

      Red   is preceived to account for 29.9% of the brightness
      Green is preceived to account for 58.7% of the brightness
      Blue  is preceived to account for 11.4% of the brightness


===================================
 for loop


   The for loop specifies the the "parts" of the while loop
      on one line.

     1.   initialization
     2.   condition
     3.   increment

    Syntax for the for loop

       for  <loopCounterVar> in  <sequence> :
          <loopBodyStatements>

   The simplest way to specify a <sequence> it the use of
      the range ( ) library function

      range(<start>, <stop> , <step>)

       <start>: Starting number of the sequence.
       <stop>: Generate numbers up to, but not including this number.
       <step>: Difference between each number in the sequence.

    For example that generates a sequence of 10 values

        range ( 0 , 10, 1 )

   To loop 10 times with a for loop, the code would be

      for count in range ( 0, 10, 1) :
         print count