问frame.shape NameError:未定义名称“frame”

EN

import tensorflow as tf
from tf_bodypix.api import download_model, load_model, BodyPixModelPaths
import cv2
from matplotlib import pyplot as plt
import numpy as np


# # 2. Detections

# In[2]:

load_model(download_model(BodyPixModelPaths.MOBILENET_FLOAT_50_STRIDE_16))

# In[3]:

bodypix_model = load_model(download_model(BodyPixModelPaths.MOBILENET_FLOAT_50_STRIDE_16))

# In[27]:

# get vid cap device
cap = cv2.VideoCapture(0) 

# loop through frame
while cap.isOpened(): 
    ret, frame = cap.read()
    
    # BodyPix Detections
    result = bodypix_model.predict_single(frame)
    mask = result.get_mask(threshold=0.5).numpy().astype(np.uint8)
    masked_image = cv2.bitwise_and(frame, frame, mask=mask)
    
    # Show result to user on desktop
    cv2.imshow('BodyPix', masked_image)
    
    # Break loop outcome 
    if cv2.waitKey(10) & 0xFF == ord('q'):
        break

cap.release() # Releases webcam or capture device
cv2.destroyAllWindows() # Closes imshow frames

# # 3. Add Virtual Background

# In[12]:

img = cv2.imread('beach.jpg')
img = img[:480, :640, :]


# In[13]:


plt.imshow(cv2.cvtColor(img, cv2.COLOR_BGR2RGB))

# In[14]:

img.shape


# In[15]:

frame.shape

# In[24]:

plt.imshow(mask)


# In[23]:


plt.imshow(np.where(np.add(mask, -1) == -1, 1, np.add(mask, -1)))

# In[ ]:

# get vid cap device
cap = cv2.VideoCapture(0) 

# loop through frame
while cap.isOpened(): 
    ret, frame = cap.read()
    
    # BodyPix Detections
    result = bodypix_model.predict_single(frame)
    mask = result.get_mask(threshold=0.5).numpy().astype(np.uint8)
    masked_image = cv2.bitwise_and(frame, frame, mask=mask)
    
    # Apply virtual background
    neg = np.add(mask, -1)
    inverse = np.where(neg==-1, 1, neg).astype(np.uint8)
    masked_background = cv2.bitwise_and(img, img, mask=inverse)
    final = cv2.add(masked_image, masked_background)
    
    # Show result to user on desktop
    cv2.imshow('BodyPix', final)
    
    # Break loop outcome 
    if cv2.waitKey(10) & 0xFF == ord('q'):
        break

cap.release() # Releases webcam or capture device
cv2.destroyAllWindows() # Closes imshow frames