Can anyone spot where I'm going wrong here. It should be creating grayscale copies of images in one folder and saving them in another folder. Could it be to do with the way im referencing the file locations. Folder permissions on both folders are 777

function grayscalecopy($targetfile, $outputfile){
$size = GetImageSize($targetfile);
$width = $size[1];
$height = $size[0];
$canvas = imagecreatetruecolor($width, $height);
$sourceimage = imagecreatefromjpeg($targetfile);
imagefilter($sourceimage, IMG_FILTER_GRAYSCALE);
imagecopy($canvas, $sourceimage, 0, 0, 0, 0, $width, $height);
imagejpeg($canvas, $outputfile, 95);
imagedestroy($sourceimage);
imagedestroy($canvas);
echo "Converted ".$targetfile." to grayscale as ".$outputfile." ".$width."x".$height."<br/>";
}

$serverfiles = glob("artworkimages/thumbs/*.*");
//$numbertocache = count($serverfiles);
$numbertocache = 10;
for ($i=0; $i<$numbertocache; $i++)
{
    $serverfilesshort=explode("/",$serverfiles[$i]);
    $serverfilesshort=$serverfilesshort[count($serverfilesshort)-1];
    grayscalecopy($serverfiles[$i], "artworkimages/thumbs/grays/".$serverfilesshort);
}