public static function border($image, array $params = array())
{
$params = array_merge(array('color' => '#333', 'size' => 1), $params);
$size = Helper::range($params['size'], 1, 1000);
$rgba = Helper::normalizeColor($params['color']);
$width = imagesx($image);
$height = imagesy($image);
$x1 = 0;
$y1 = 0;
$x2 = $width - 1;
$y2 = $height - 1;
$color = imagecolorallocatealpha($image, $rgba[0], $rgba[1], $rgba[2], $rgba[3]);
for ($i = 0; $i < $size; $i++) {
imagerectangle($image, $x1++, $y1++, $x2--, $y2--, $color);
}
}