تبدیل PNG به JPG در PHP

<?php
require_once("http://localhost:8080/JavaBridge/java/Java.inc");
require_once("lib/aspose.slides.php");

$pres = new Presentation();
try
{
    $slide = $pres->getSlides()->get_Item(0);
    
    $filename = 'image.png';
    $f = fopen($filename, 'r');
    if ($f) {
        $contents = fread($f, filesize($filename));
        fclose($f);
    }
    
    $image = $pres->getImages()->addImage($contents);
    $slide->getShapes()->addPictureFrame(ShapeType::Rectangle, 10, 10, 100, 100, $image);

    for ($i = 0; $i < java_values($pres->getSlides()->size()); $i++)
    {
        $bmp = $pres->getSlides()->get_Item($i)->getThumbnail(2, 2);
        $imageio = new Java("javax.imageio.ImageIO");
        $javafile = new Java("java.io.File", "slide_". $i .".jpg");
        $imageio->write($bmp, "JPG", $javafile);
    }
}
finally
{
    if ($pres != null) $pres->dispose();
}
?>