gistfile1.py

def adjust_colours(target_pic, reference_pic):
    '''Takes target pic and adjusts it's average RGB values to reference pic's RGB values...
    '''

    target_red_avg = red_average(target_picture)
    reference_red_avg = red_average(reference_picture)
    red_scale_factor = reference_red_avg/target_red_avg

    target_blue_avg = blue_average(target_picture)
    reference_blue_avg = blue_average(reference_picture)
    blue_scale_factor = reference_blue_avg/target_blue_avg

    target_green_avg = green_average(target_picture)
    reference_green_avg = green_average(reference_picture)
    green_scale_factor = reference_green_avg/target_green_avg

    to_return = media.copy(target_pic)
    for pix in to_return:
      # There's a slightly more concise way of doing this, but leaving it like
      # this for pedagogical purposes.
      new_red = red_scale_factor * media.get_red(pix)
      media.set_red(pix, new_red)

      new_blue = blue_scale_factor * media.get_blue(pix)
      media.set_blue(pix, new_blue)

      new_green = green_scale_factor * media.get_green(pix)
      media.set_green(pix, new_green)

    return to_return