title: how to read a neural network model with openCV
body: <p>I am using <code>cv2.dnn.readNet</code> to use a neural network model for text detection in an image. it takes the following error and I don't have any idea what it is saying.</p>
  
  <p>here's my pice of code:</p>
  
  <pre><code>nn = cv2.dnn.readNet('frozen_east_text_detection.pb')
  </code></pre>
  
  <p>The error is:</p>
  
  <pre><code>error: OpenCV(4.1.2) /io/opencv/modules/dnn/src/tensorflow/tf_io.cpp:42: error: (-2:Unspecified error) FAILED: ReadProtoFromBinaryFile(param_file, param). Failed to parse GraphDef file: frozen_east_text_detection.pb in function 'ReadTFNetParamsFromBinaryFileOrDie'
  </code></pre>
  
  <p>I should say Im writing at google colab, thank u...</p>