title: Caffe convert_imageset with one class/ label
body: <p>I want to create an lmdb dataset from images which part of them contain the feature I want caffe to learn, and part of them don't.<br>
  My question is - in the text input file transferred to convert_imageset - how should I label those images that don't contain the feature?<br>
  I know the format is</p>
  
  <pre><code>PATH_TO_IMAGE LABEL
  PATH_TO_IMAGE LABEL
  PATH_TO_IMAGE LABEL
  </code></pre>
  
  <p>But which label should I assign to images <strong>without</strong> the feature?<br>
  For example, img1.jpg contain the feature, img2.jpg and img3.jpg don't.
  So should the text file look like -</p>
  
  <pre><code>img1.jpg 0
  img2.jpg 1?
  img3.jpg 1?
  </code></pre>
  
  <p>Thanks!</p>