title: ImageMagick: No decode delegate for this image format `' @ error/constitute.c/ReadImage/504
body: <p><strong>Problem:</strong> ImageMagick convert is unable to crop image. It looks like it doesn't recognize the image type?</p>
  <p><strong>What I've Tried:</strong></p>
  <p>I've searched around online and I've seen several similar issues but not mine.
  I've attempted their solutions including</p>
  <ul>
  <li>Uninstalling and reinstalling ImageMagick via brew.</li>
  <li>identify -list format (JPEG, GIF, PNG, TIFF, etc were all there and all had rw permissions)</li>
  <li>convert -version <em>(png is is among the built-in delegates)</em></li>
  <li>convert pic1.png pic1-jpg.jpg <em>(this worked fine)</em></li>
  <li>convert pic1-jpg.jpg pic1-jpg.jpg <em>(this worked fine)</em></li>
  <li>convert pic1-jpg.jpg 805X972+34+94 pic1-jpg-crop.jpg <em>(this gave the same error as for png as shown below)</em></li>
  </ul>
  <p> </p>
  <p>I'm working on Mac OSX El Capitan and everything else in terminal works fine. ImageMagick was already installed.</p>
  <p><strong>When I run:</strong></p>
  <pre><code>$ convert /Users/Innovate/Desktop/crop/2015-04-26-GinaDate13_487.png 805X972+34+94 /Users/Innovate/Desktop/crop/2015-04-26-GinaDate13_487-cropped.png 
  </code></pre>
  <p><strong>I get:</strong></p>
  <blockquote>
  <p>convert: unable to open image `805X972+34+94': No such file or directory @ error/blob.c/OpenBlob/2702.</p>
  <p>convert: no decode delegate for this image format `' @ error/constitute.c/ReadImage/504.</p>
  <p>no decode delegate for this image format `' @ error/constitute.c/ReadImage/504</p>
  </blockquote>
  <p>In the other posts on this issue, people get</p>
  <blockquote>
  <p>convert no decode delegate for this image format `PNG'</p>
  </blockquote>
  <p>Or similar (except with their image type or filename and image type)</p>
  <p> </p>
  <p>However, mine doesn't say anything about image file type...</p>
  <p>I have not tried uninstalling ImageMagick then installing it manually from sources because I'm not very confident at doing that... (this solution was shown: <a href="https://stackoverflow.com/a/34633084/5398660">https://stackoverflow.com/a/34633084/5398660</a> )</p>
  <p>Does anyone know what might be going on?</p>
  <p>Also, can anyone help me interpret the <em>@ error/constitute.c/ReadImage/504</em> part? I'm looking at the code for <a href="http://www.imagemagick.org/api/MagickCore/constitute_8c_source.html" rel="noreferrer">constitute.c</a>  but I'm not sure if I can get useful information from it to solve my problem (I only know a bit of C)</p>
  <p>Thank you!</p>