php实现ppt转图片，php调用com组件问题

<?php
$powerpnt = new COM("powerpoint.application") or die("Unable to instantiate Powerpoint");
$file='1.ppt';
echo realpath($file);

$addr = $_SERVER['DOCUMENT_ROOT'].'/ppt/1.ppt';
echo $addr;
$presentation = $powerpnt->Presentations->Open($addr, false, false, false) or die("Unable to open presentation");


$presentation->Fonts->Replace('黑体','幼圆');
$presentation->Fonts->Replace('MS Gothic','幼圆');
$presentation->Fonts->Replace('方正粗倩简体','幼圆');
$presentation->Fonts->Replace('方正小标宋简体','幼圆');
$presentation->Fonts->Replace('Arial Black','幼圆');
$presentation->Fonts->Replace('华文中宋','幼圆');
$presentation->Fonts->Replace('Arial Unicode MS','幼圆');
$presentation->Fonts->Replace('方正细圆简体','幼圆');
$presentation->Fonts->Replace('Times New Roman','幼圆');


foreach($presentation->Fonts as $c)
{
	echo $c->name."<br />";
	//echo $c->Replace('','');
}


foreach($presentation->Slides as $slide)
{
$slideName = "Slide_" . $slide->SlideNumber;
$uploadsFolder = 'iii';
$exportFolder = realpath($uploadsFolder);
$slide->Export($exportFolder."//".$slideName.".jpg", "jpg", "1920", "1080");
}
$presentation->Close();
$powerpnt->Quit();
$powerpnt = null;
?>