detect rectangle in image and crop

Here is My Version

import cv2
import numpy as np

fileName = ['9','8','7','6','5','4','3','2','1','0']

img = cv2.imread('Data\Scan_20170612_17.jpg')

gray = cv2.cvtColor(img, cv2.COLOR_BGR2GRAY)
gray = cv2.bilateralFilter(gray, 11, 17, 17)

kernel = np.ones((5,5),np.uint8)
erosion = cv2.erode(gray,kernel,iterations = 2)
kernel = np.ones((4,4),np.uint8)
dilation = cv2.dilate(erosion,kernel,iterations = 2)

edged = cv2.Canny(dilation, 30, 200)

_, contours, hierarchy = cv2.findContours(edged, cv2.RETR_TREE, cv2.CHAIN_APPROX_SIMPLE)

rects = [cv2.boundingRect(cnt) for cnt in contours]
rects = sorted(rects,key=lambda  x:x[1],reverse=True)


i = -1
j = 1
y_old = 5000
x_old = 5000
for rect in rects:
    x,y,w,h = rect
    area = w * h

    if area > 47000 and area < 70000:

        if (y_old - y) > 200:
            i += 1
            y_old = y

        if abs(x_old - x) > 300:
            x_old = x
            x,y,w,h = rect

            out = img[y+10:y+h-10,x+10:x+w-10]
            cv2.imwrite('cropped\\' + fileName[i] + '_' + str(j) + '.jpg', out)

            j+=1