当我创建没有颜色的图像时，有时我会得到垃圾（随机颜色、点或线）
image = Image.new("RGBA", (256, 256), None)
# draw a rectangle with rounded corners
image = draw_corner_box(image, radius=10)
# draw a rectangle with rounded corners and apply blur,
# paste image in the result and return
image = draw_shadow_box(image, radius=10)
image.save("image.png", "PNG")
完整图像
缩放图像
