The problem could be that the DPI is not stored in the PNG file. And after you save it in an editor it is saved. The DPI is not mandatory in PNG ([url]http://www.libpng.org/pub/png/spec/1.2/PNG-Chunks.html#C.pHYs[/url]) so the PHPDOCX code should be aware of that. I mad a quick fix for the function getDpiPng in classes/CreateImage.inc:
[code] private function getDpiPng($filename)
{
// open the file and read first 20 bytes.
$a = fopen($filename, 'r');
$string = fread($a, 1000);
$aux = strpos($string, 'pHYs');
//some png files do not have the pHYs, so we return a default
if ($aux === FALSE) return array(2835,2835);
$data = bin2hex(substr($string, $aux + strlen('pHYs'), 16));
fclose($a);
$x = substr($data, 0, 8);
$y = substr($data, 8, 8);
return array(hexdec($x), hexdec($y));
}[/code]