python - 如何裁剪最大的矩形并应用环绕变换

Question

嗨，有人可以帮我调试我的代码吗？我正在裁剪最大的矩形并将其应用于变换。我上传了图片，因此您可以看到它。我在树莓派和opencv 3.3.0上使用python 2.7

import cv2
import os
import numpy as np

im = cv2.imread('image.png')

# Use a blurring effect, to (hopefully) remove these high frequency 
#noises.

image_blurred = cv2.GaussianBlur(im,(3,3),0)



#apply a canny edge-detector

edges = cv2.Canny(image_blurred,100,300,apertureSize = 3)



#finding the contours in the image

contours,hierarchy = cv2.findContours(edges,cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)



#to find the biggest rectangle. For each contour cnt, first find the 
#convex hull, then use approaxPolyDP to simplify the contour as much as 
#possible.

hull = cv2.convexHull(cnt)
simplified_cnt = cv2.approxPolyDP(hull,0.001*cv2.arcLength(hull,True),True)



#after finding (hopefully) the right quadrilateral, is transforming back 
#to a rectangle. For this you can use findHomography to come up with a 
#transformation matrix.

(H,mask) = cv2.findHomography(cnt.astype('single'),np.array([[[0., 0.]],[[2150., 0.]],[[2150., 2800.]],[[0.,2800.]]],dtype=np.single))



#for the final tranformation on crop image using warpPerspective

final_image = cv2.warpPerspective(image,H,(2150, 2800))

cv2.imshow("Show",final_image)

cv2.waitKey(0)

这是我的代码，但我总是这样。



这是我得到的错误

追溯(最近一次通话):
在第11行的文件“crop.py”中
等高线，层次结构= cv2.findContours(edges，cv2.RETR_EXTERNAL，cv2.CHAIN_APPROX_SIMPLE)
ValueError:太多值无法解包

Answer 1

看一下文档，findContours返回三个值，用法如下:

im2, contours, hierarchy = cv2.findContours(thresh,cv2.RETR_TREE,cv2.CHAIN_APPROX_SIMPLE)