// delete all files from new/new/uploads/newfiles first

$imagefolder = 'new/new/uploads';
$log = $imagefolder . "/newfiles/log.txt";
$images = GLOB($imagefolder . "/" . "*{.jpg,.jpeg,.png,.gif}", GLOB_BRACE);
foreach ($images as $img) {
    $oldfilename = basename($img);
    $newfilename = preg_replace("/[\s_]/", "-", $oldfilename); // replace space with dash
    if (rename($img, $imagefolder . '/newfiles/' . $newfilename)) {
        $data = "original file: {$img} to: {$newfilename} status: Successful\r\n";
    } else {
        $data = "original file: {$img} to: {$newfilename} status: Fail\r\n";
    }
    file_put_contents($log, $data, FILE_APPEND); // create log file
}