title: PNG optimization issue using pngcrush tool
body: <p>I have few queries on "pngcrush" tool.</p>
  
  <p>While xcode build process,</p>
  
  <ol>
  <li>I am setting option "Compress PNG Files" to "YES" and then checked the binary and image size.</li>
  <li>Then in my another build process, I am setting option "Compress PNG Files" to "NO" and then again checked the binary and image size.</li>
  </ol>
  
  <p>But, there is no any difference between 1. and 2. in binary/image size.</p>
  
  <p>Why "pngcrush" tool is not optimizing the png files?</p>
  
  <p>Any help would be great.</p>
  
  <p>Thanks in advance.</p>
  
  <p>Regards,
  Devendra</p>