function imagewatermark($watermark,$image,$opacity,$filename)
{
	$split_extenstion = explode(".",$image);
	$getExtenstionOfImage = $split_extenstion[(sizeof($split_extenstion) - 1)]; 
	
	switch ($getExtenstionOfImage)
	{
		case "jpeg":
			$image_handle = imagecreatefromjpeg($image); 
		break;
		case "jpg":
			$image_handle = imagecreatefromjpeg($image); 
		break;
		case "gif":
			$image_handle = imagecreatefromgif($image);
		break;
		case "png":
			$image_handle = imagecreatefrompng($image);
		break;
		default :
			return false;
			break;
				
	}
	
	$image_watermark = imagecreatefrompng($watermark);			
	
	$watermark_size = getimagesize($watermark);
	$image_size = getimagesize($image);
	$position_x = $image_size[0] - $watermark_size[0] - 5;
	$position_y = $image_size[1] - $watermark_size[1] - 5;
	
	imagecopymerge($image_handle,$image_watermark,$position_x,$position_y,0,0,$watermark_width,$watermark_height,$opacity); 
	
	imagejpeg($image_handle,$filename,100);
}