#
# Lighten.py, James Tam
# Version 2: June 10, 2009
#  
# This program takes the picture called mediumLion.jpg (which must be in the same location where the
# JES program resides) and lightens the image pixel-by-pixel. The modified image is then saved at
# the location specified by the user (at the start of the program). Be sure that the name of the image
# includes the proper filename suffix e.g., mediumLion.jpg is a JPEG type of image so it needs to end
# in the suffix ".jpg" in order for the operating system to properly recognize the file and image type.
# Also the complete location where the image is to be saved must also be specified.
# e.g., when prompted for a location and file name the user could specify the path as "C:\JES\modified.jpg"
# A new image called 'modified.jpg' would appear in the 'JES' folder which resides on the 'C' drive of the
# computer where JES is running.

def lighten ():

  # Prompt the user for the location and filename of the modified image.
  path = raw_input ("Enter the location and name of the file to save the changes to (make sure it ends with the proper suffix: ")

  # The name of the picture to be modified is fixed. To run this program properly an image with this exact name must 
  # reside in the same folder as the "JES" program or the program must be modified to accomodate something else. Caution:
  # using an image that is large will take a long time for this program to execute!
  aPicture = makePicture ("mediumLion.jpg")

  # Show the original picture.
  show (aPicture)

  # Get all the pictures from the picture (so the program can iterate or step through them in the loop.
  allPixels = getPixels (aPicture)

  # Iterate through each pixel in the image.
  for pixel in allPixels:

    # Get and store the current color (red, blue, green) levels for each pixel.
    red = getRed (pixel)
    blue = getBlue (pixel)
    green = getGreen (pixel)

    # If increasing the color level of the pixel won't push it past the allowable maximum of 255 then lighten up
    # the pixel's color level.
    if ((red + 50) <= 255):
      setRed (pixel, (red+50))
    if ((blue + 50) <= 255):
      setBlue (pixel, (blue+50))
    if ((green + 50) <= 255):
      setGreen (pixel, (green+50))
   
  # After all the sub-pixels of each pixel in the image have been modified and the loop has been completed show the 
  # modified picture onscreen.
  repaint (aPicture)

  # Save the modified picture to the location and under the filename specified by the user at the start of the program.
  writePictureTo (aPicture, path)