title: Tensorflow Lite - ValueError: Cannot set tensor: Dimension mismatch
body: <p>This is probably going to be a stupid question but I am new to machine learning and Tensorflow.
  I am trying to run object detection API on Raspberry Pi using <strong>Tensorflow Lite</strong>. I am trying to modify my code with the help of this example</p>
  
  <pre><code>https://github.com/freedomtan/tensorflow/blob/deeplab_tflite_python/tensorflow/contrib/lite/examples/python/object_detection.py
  </code></pre>
  
  <p>This piece of code will detect object from a image. But instead of a image I want to detect object on real time through Pi camera.
  I tried to modified this code to read input from camera instead of image. Here is my piece of code -</p>
  
  <pre><code>import numpy as np
  from tensorflow.contrib.lite.python import interpreter as interpreter_wrapper
  import cv2
  
  cap = cv2.VideoCapture(0)
  ret, image_np = cap.read()
  
  PATH_TO_MODEL = "ssd_mobilenet_v1_coco.tflite"
  
  interpreter = tf.contrib.lite.Interpreter(model_path=PATH_TO_MODEL)
  interpreter.allocate_tensors()
  
  input_details = interpreter.get_input_details()
  output_details = interpreter.get_output_details()
  
  while True:
    # NxHxWxC, H:1, W:2
    height = input_details[0]['shape'][1]
    width = input_details[0]['shape'][2]
    ret, image_np = cap.read()
  
    image_np_expanded = np.expand_dims(image_np, axis=0)
    #if floating_model:
    image_np_expanded = (np.float32(image_np_expanded) - input_mean) / input_std
  
    #HERE I AM GETTING ERROR
    interpreter.set_tensor(input_details[0]['index'], image_np_expanded)
  
    if cv2.waitKey(25) &amp; 0xFF == ord('q'):
      cv2.destroyAllWindows()
      break
  </code></pre>
  
  <p>but I am getting this error -</p>
  
  <pre><code>Traceback (most recent call last):
    File "New_object_detection.py", line 257, in &lt;module&gt;
      interpreter.set_tensor(input_details[0]['index'], image_np_expanded)
    File "/home/saurabh/.local/lib/python3.6/site-packages/tensorflow/contrib/lite/python/interpreter.py", line 151, in set_tensor
      self._interpreter.SetTensor(tensor_index, value)
    File "/home/saurabh/.local/lib/python3.6/site-packages/tensorflow/contrib/lite/python/interpreter_wrapper/tensorflow_wrap_interpreter_wrapper.py", line 133, in SetTensor
      return _tensorflow_wrap_interpreter_wrapper.InterpreterWrapper_SetTensor(self, i, value)
  ValueError: Cannot set tensor: Dimension mismatch
  </code></pre>
  
  <p>Can anyone please tell me how to fix this error or suggest a tutorial for the same?</p>