title: "imagecreatefrompng" Not working on server but in localhost
body: <p>I used <code>imagecreatefrompng</code> function to generate captcha. It works fine in localhost and not in web server
  this is my code</p>
  
  <pre><code>$captcha_base_img = base_url("assets/images/captcha_back.png");
              $image = imagecreatefrompng($captcha_base_img); 
  //returns an image identifier representing a black image of the specified size(w,h)
  </code></pre>
  
  <p>php info</p>
  
  <blockquote>
    <p>gd GD Support enabled GD Version  bundled (2.1.0 compatible) FreeType
    Support   enabled FreeType Linkage    with freetype FreeType Version  2.3.11
    GIF Read Support  enabled GIF Create Support  enabled JPEG
    Support   enabled libJPEG Version 6b PNG Support  enabled libPNG
    Version   1.2.49 WBMP Support enabled XBM Support enabled</p>
  </blockquote>
  
  <p>what would be the reason? </p>
  
  <pre><code>$image returns false; 
  </code></pre>
  
  <p>it is a png image</p>
  
  <p>error log : </p>
  
  <blockquote>
    <p>Warning --> imagecreatefrompng(<a href="http://url/captcha_back.png" rel="nofollow noreferrer">http://url/captcha_back.png</a>) [function.imagecreatefrompng]: failed to open stream: HTTP request failed! HTTP/1.1 404 Not Found</p>
  </blockquote>