title: Random crop and bounding boxes in tensorflow
body: <p>I want to add a data augmentation on the WiderFace dataset and I would like to know, how is it possible to random crop an image and only keep the bouding box of faces with the center inside the crop using tensorflow ?</p>
  
  <p>I have already try to implement a solution but I use TFRecords and the TfExampleDecoder and the shape of the input image is set to <code>[None, None, 3]</code> during the process, so no way to get the shape of the image and do it by myself.</p>