pythonnumpyopencv

TypeError: src is not a numpy array, neither a scalar What is wrong in my code?

I got an error,TypeError: src is not a numpy array, neither a scalar.

Traceback says 
Traceback (most recent call last):
  File "img.py", line 19, in <module>
    gray = cv2.cvtColor(images,cv2.COLOR_BGR2GRAY)
TypeError: src is not a numpy array, neither a scalar

. I wrote in img.py

import numpy as np
import cv2
import glob
from PIL import Image

# termination criteria
criteria = (cv2.TERM_CRITERIA_EPS + cv2.TERM_CRITERIA_MAX_ITER, 30, 0.001)

# prepare object points, like (0,0,0), (1,0,0), (2,0,0) ....,(6,5,0)
objp = np.zeros((6*7,3), np.float32)
objp[:,:2] = np.mgrid[0:7,0:6].T.reshape(-1,2)

# Arrays to store object points and image points from all the images.
objpoints = [] # 3d point in real world space
imgpoints = [] # 2d points in image plane.

images = Image.open('photo.jpg')

gray = cv2.cvtColor(images,cv2.COLOR_BGR2GRAY)

# Find the chess board corners
ret, corners = cv2.findChessboardCorners(gray, (7,6),None)

# If found, add object points, image points (after refining them)
if ret == True:
   objpoints.append(objp)

   corners2 = cv2.cornerSubPix(gray,corners,(11,11),(-1,-1),criteria)
   imgpoints.append(corners2)

   # Draw and display the corners
   img = cv2.drawChessboardCorners(img, (7,6), corners2,ret)
   cv2.imshow('img',img)
   cv2.waitKey(500)

cv2.destroyAllWindows()

I searched this error, and i found this question exceptions.TypeError: src is not a numpy array, neither a scalar ,but I already use cv2.COLOR_BGR2GRAY in cvtColor method so I really cannot understand why this error happens.And I really cannot understand the meaning of src. What is wrong in my code?How should I fix this? I referenced this opencv document https://docs.opencv.org/3.4.0/d9/df8/tutorial_root.html .

Solution

  • The problem is here:

    images = Image.open('photo.jpg')

gray = cv2.cvtColor(images,cv2.COLOR_BGR2GRAY)

    OpenCV uses numpy arrays. So you'd need to convert that PIL image to a numpy array. Perhaps something like this:

    images = np.array(Image.open('photo.jpg'))

gray = cv2.cvtColor(images,cv2.COLOR_BGR2GRAY)