import matplotlib.pyplot as plt
import matplotlib.image as pli
from skimage.filters import threshold_otsu as otsu
from PIL import Image

cnh_cinza = Image.open("cnh.jpg").convert('L')
cnh_cinza.save('cnhcinza.jpg')

img = pli.imread('cnhcinza.jpg')
imagem = Image.open('cnhcinza.jpg')


limiar = otsu(img)

mask = img < limiar

msk = Image.fromarray(mask,'L')

caixa = msk.getbbox()

corte = imagem.crop(caixa)



_,ax = plt.subplots (1,3)
ax[0].imshow (img,cmap='gray')
ax[1].imshow (mask,cmap='gray')
ax[2].imshow (corte,cmap='gray')
plt.show()