water mark in image

/*
+------------------------------------------------------------------+
Function will be use for excel download.
@params-> $fullname : name of the file
+------------------------------------------------------------------+
*/
function watermark($fullname)
{
$this->load->library('image_lib');
$configwater['image_library'] = 'gd2';
$configwater['wm_text'] = "FREE 2000544";
$configwater['wm_type'] = 'text';
$configwater['source_image'] = 'uploads/coupon/'.$fullname;
//$configwater['new_image'] = base_url() .'uploads/coupon/'. basename($configwater['source_image'],'.png') .'_watermark.png' ;
$configwater['wm_font_path']= 'system/fonts/texb.ttf';
$configwater['wm_font_size'] = '20';
$configwater['wm_vrt_alignment'] = 'bottom';
$configwater['wm_hor_alignment'] = 'center';

$this->image_lib->initialize($configwater);
$this->image_lib->watermark();
$this->image_lib->clear();
}

/*