Value Errorについて

Question

img_bgr=cv2.imread('IMG_1565.JPG')
img_gray=cv2.cvtColor(img_bgr,cv2.COLOR_BGR2GRAY)
retval,thresh=cv2.threshold(img_gray,88,255,0)
img,contours,hierarchy=cv2.findContours(thresh, cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)

result_img=cv2.drawContours(img,contours,-1,(0,0,255),3)

plt.imshow(result_img);
plt.show()
---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
<ipython-input-24-15ddabad3493> in <module>()
      2 img_gray=cv2.cvtColor(img_bgr,cv2.COLOR_BGR2GRAY)
      3 retval,thresh=cv2.threshold(img_gray,88,255,0)
----> 4 img,contours,hierarchy=cv2.findContours(thresh, cv2.RETR_EXTERNAL,cv2.CHAIN_APPROX_SIMPLE)
      5 
      6 result_img=cv2.drawContours(img,contours,-1,(0,0,255),3)

ValueError: not enough values to unpack (expected 3, got 2)

これはどこの引数がおかしいのでしょうか？

Answer 1

画像認識で輪郭抽出に用いるcv2のValueErrorが解決できない