PHP fails to draw pictures, which can be solved by clearing the cache ob_clean.

<code><span>header</span>(<span>"Content-type: image/png"</span>);
<span>$img</span><span>=</span>imagecreatetruecolor(<span>200</span>,<span>200</span>);
imagepng(<span>$img</span>);
imagedestroy(<span>$img</span>);</code>

<code><span><span><?php </span>
ob_clean();
header(<span>"Content-type: image/png"</span>);
<span>$img</span>=imagecreatetruecolor(<span>200</span>,<span>200</span>);
imagepng(<span>$img</span>);
imagedestroy(<span>$img</span>);
<span>?&gt;</span></span></span></code>