CI: image resize

ci_image_resize.php

function _resize($a,$target_width=600,$target_height=600,$marker='thumb_') {
        $this->load->library('image_lib');
        $ret = array('poza'=>'','error'=>'');
        $size = getimagesize('./uploads/'.$a['file_name']);
        $a['image_width'] = $size[0];
        $a['image_height'] = $size[1];
        if ($a['image_width'] > $target_width || $a['image_height'] > $target_height)
        {
          if ($a['image_width'] > $target_width && $a['image_height'] > $target_height)
            $master_dim = 'auto';
          elseif ($a['image_width'] > $target_width)
            $master_dim = 'width';
          else
            $master_dim = 'height';   
            $config2['image_library'] = 'gd2';
            $config2['source_image'] = FCPATH . '/uploads/'.$a['file_name'];
            $config2['create_thumb'] = TRUE;
            $config2['maintain_ratio'] = TRUE;
            $config2['width'] = $target_width;
            $config2['height'] = $target_height;
            $config2['master_dim'] = $master_dim;
            $config2['new_image'] = FCPATH . '/uploads/'.$marker.$a['file_name'];
            $config2['thumb_marker'] = '';
            $this->image_lib->initialize($config2);
            if ( ! $this->image_lib->resize())
              $ret['error'] = '<div class="error">'.$this->image_lib->display_errors().'</div>';
            else $ret['poza'] = $a['file_name'];
        }
        else $ret['poza'] = $a['file_name'];
        return $ret;
    }