Short snippet how to draw canvas with rectangles and make thumbnail of image with Pillow.
from PIL import Image, ImageDraw
# size of image
canvas = (400, 300)
# scale ration
scale = 5
thumb = canvas[0]/scale, canvas[1]/scale
# rectangles (width, height, left position, top position)
frames = [(50, 50, 5, 5), (60, 60, 100, 50), (100, 100, 205, 120)]
# init canvas
im = Image.new('RGBA', canvas, (255, 255, 255, 255))
draw = ImageDraw.Draw(im)
# draw rectangles
for frame in frames:
x1, y1 = frame[2], frame[3]
x2, y2 = frame[2] + frame[0], frame[3] + frame[1]
draw.rectangle([x1, y1, x2, y2], outline=(0, 0, 0, 255))
# make thumbnail
im.thumbnail(thumb)
# save image
im.save('/home/proft/temp/im.png')