title: no decode delegate for this image format `PNG' ImageMagick CentOS
body: <p>I'm trying to use ImageMagick in CentOS to generate pdf documents and convert PNG images. ImageMagic is already installed and imagic extension is loaded and working in PHP 5.5 but when I try to generate PDF or convert images I get the follow error: 
  <strong>no decode delegate for this image format `PNG'</strong>  </p>
  
  <p>I've already installed libpng and reinstalled ImageMagic but the problem continues</p>