php image rotator

<?php
header('Content-Type: text/html; charset=UTF-8');
header('Cache-Control: no-cache, must-revalidate');
header('Expires: Sat, 09 Jan 2009 09:09:09 GMT');

// the folder to read pictures from
// default: '..'  (parent folder)
$folder = '..';

// the picture formats to support
$formats = array(
        'jpg'  => 'image/jpg',
        'jpeg' => 'image/jpeg',
        'png'  => 'image/png',
        'gif'  => 'image/gif'
);

if (substr($folder, -1) != '/')
{
        $folder .= '/';
}
$image = '';
$files = array();
$h = opendir($folder);
while (false !== ($file = readdir($h)))
{
        $ext = '';
        $info = pathinfo($file);
        if (isset($info['extension']))
        {
                $ext = $info['extension'];
        }
        if (isset($formats[strtolower($ext)]))
        {
                $files[] = $file;
        }
}
closedir($h);
if (count($files) > 0)
{
        $image = time() % count($files);
        $image = $folder.$files[$image];
}
if (strlen($image) <3 )
{
        die('no pix (sorry bro)');
}

// Setting the picture header
$info = pathinfo($image);
$ext = $info['extension'];
$mime = $formats[strtolower($ext)];
header('Content-Type: ' . $mime);

// Flushing the image to output
set_time_limit(5);
$image = @fopen($image, 'rb');
while (!feof($image))
{
        print(@fread($image, 8192));
        ob_flush();
        flush();
}

// the missing PHP closing tag
// (questionmark and greater-than sign)
// is intentional to prevent image corruption