from PIL import Image, ImageDraw
 
im = Image.new('RGB', (300, 300), (255, 255, 255))
draw = ImageDraw.Draw(im)

west_north = (100, 100)
east_south = (200, 200)
outline_color = (128, 128, 128)

draw.rectangle([west_north, east_south],    
    outline=outline_color)
 
im.show()