image_functions_advanced.py

import media

COLOUR_MAX = 255
COLOUR_MIN = 0

def get_picture():
  '''Solicit user input to select a file and load it as a Picture.
  Return the Picture.
  '''
  filename= media.choose_file()
  pic = media.load_picture(filename)
  return pic

def set_colour(picture, colour, value):
  for pixel in picture:
    getattr(media, 'set_%s' % colour)(pixel, value)

def maximize_red(pic):
  '''Maximize the red component of every pixel in the Picture pic.
  '''
  set_colour(pic, 'red', COLOUR_MAX)

def remove_blue(pic):
  set_colour(pic, 'blue', COLOUR_MIN)

def halve_green(pic):
  set_colour(pic, 'green', COLOUR_MAX/2)

if __name__ == '__main__':
  pic = get_picture()
  maximize_red(pic)
  remove_blue(pic)
  halve_green(pic)
  media.show(pic)