Python 3.x 摄像机标定中的未定义名称问题

我使用的代码与OpenCv教程提供的代码相同，它在几周前还在运行，今天我尝试运行它，它说灰色名称没有定义！！有人能帮我找出错误吗

import numpy as np
#import matplotlib.pyplot as plt
import cv2
import glob
import os

def draw(img, corners, imgpts):
    corner = tuple(corners[0].ravel())
    img = cv2.line(img, corner, tuple(imgpts[0].ravel()), (255,0,0), 5)
    img = cv2.line(img, corner, tuple(imgpts[1].ravel()), (0,255,0), 5)
    img = cv2.line(img, corner, tuple(imgpts[2].ravel()), (0,0,255), 5)
    return img
 # 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((7*7,3), np.float32)
 objp[:,:2] = np.mgrid[0:7,0:7].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.
 img_dir = "C:\\Hungary\\Biblography\\Rotating Solitary Wave\\My Work\\Final Work\\Experiment1111  \\Camera Calibration\\Image Processing\\chess"
 data_path = os.path.join(img_dir,'*bmp')
 images = glob.glob(data_path)
 for fname in images:
    img = cv2.imread(fname)
    gray = cv2.cvtColor(img,cv2.COLOR_BGR2GRAY)
    # Find the chess board corners
    ret, corners = cv2.findChessboardCorners(gray, (7,7),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, (7,7), corners2,ret)
       cv2.imshow('img',img)
       cv2.waitKey(500)

 cv2.destroyAllWindows()

ret, mtx, dist, rvecs, tvecs = cv2.calibrateCamera(objpoints, imgpoints, gray.shape  [::-1],None,None)        
print('Rotation Vector, or the Angles For Each Photo: ', rvecs, '\n')
R = cv2.Rodrigues(rvecs[0])
print('The Rotation Matrix is: ', R)
print('Translation Vector: ', tvecs, '\n')
print(mtx, '\n')
print('Distortion Coefficients ', dist, '\n')
img = cv2.imread('00000274.bmp')
h, w = img.shape[:2]
newcameramtx, roi=cv2.getOptimalNewCameraMatrix(mtx,dist,(w,h),1,(w,h))
print('Camera Matrix', newcameramtx, '\n')
# undistort
dst = cv2.undistort(img, mtx, dist)  #, None, newcameramtx)
p = np.ones_like(dst)
# crop the image
x,y,w,h = roi
dst = dst[y:y+h, x:x+w]
# undistort
mapx,mapy = cv2.initUndistortRectifyMap(mtx,dist,None,newcameramtx,(w,h),5)
dst = cv2.remap(img,mapx,mapy,cv2.INTER_LINEAR)
# crop the image
x,y,w,h = roi
dst = dst[y:y+h, x:x+w]
cv2.imwrite('calibresult.png',dst)
mean_error = 0
for i in range(len(objpoints)):
   imgpoints2, _ = cv2.projectPoints(objpoints[i], rvecs[i], tvecs[i], mtx, dist)
   error = cv2.norm(imgpoints[i],imgpoints2, cv2.NORM_L2)/len(imgpoints2)
   mean_error += error
print("total error: ", mean_error/len(objpoints))

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如果您阅读opencv文档，您会发现我对代码做了一些更改，并且它正在工作，但今天它提出了关于灰名称的错误没有定义

检查一下您的路径，看看

图像

是否为空列表。在这种情况下，如果定义了

gray

变量，则不会执行for循环