define('FILESDIR', dirname(__FILE__) . DIRECTORY_SEPARATOR . 'img' . DIRECTORY_SEPARATOR);

$path = FILESDIR . 'someimage.png';

$fname = 'someimage';

if (extension_loaded('gd')) {

    $imageSize = getimagesize($path);

    $types = array(1 => 'gif', 2=> 'jpg', 3 => 'png');

    $imageType = array_key_exists($imageSize[2], $types) ? $types[$imageSize[2]] : FALSE;

    if ($imageType !== FALSE) {

        $width = $imageSize[0];

        $height = $imageSize[1];

        if ($width > 220 || $height > 176) {

            switch ($imageType) {

                case 'gif': $image = imagecreatefromgif($path);  break;

                case 'jpg': $image = imagecreatefromjpeg($path); break;

                case 'png': $image = imagecreatefrompng($path);  break;

                default:

            }

            $max = $width > $height ? 'w' : 'h';

            $new_width = 176;

            $new_height = 220;

 

            if ($max == 'w' && $width > $new_width)

                $new_height = intval(($new_width * $height) / $width);

               

            if ($max == 'h' && $height > $new_height)

                $new_width = intval(($new_height * $width) / $height);

 

            $preview = imagecreate($new_width, $new_height);

            imagecopyresized($preview, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height);

            imagepng($preview, FILESDIR . $fname . '_preview.png');

        }

    }

}