title: Tensorflow Object Dectection API : how to create tfrecords with images not containing any labels (hard negatives)?
body: <p>Hello.                                    </p>
  
  <p>I am currently using tensorflow object detection API(with Faster Rcnn)on my own dataset, for some of my labels, i've identified objects that are very likely to be detected as false positives, and i know that the API uses hard exemples mining, so what i'am trying to do it is to introduce images that contain these hard objects into the training , so that the miner can take them as hard negatives.</p>
  
  <p>following this conversation on 
    github  <a href="https://github.com/tensorflow/models/issues/2544" rel="nofollow noreferrer">https://github.com/tensorflow/models/issues/2544</a> I was told that it's possible</p>
  
  <blockquote>
    <p>You can have purely negative images and faster_rcnn models will sample
    from anchors from them.</p>
  </blockquote>
  
  <p>So my question is : how do i create tfrecords with some images not having any bounding boxes ? What do i put in the associated .xml files?</p>