Hi All
I solve this error by changing as below. But i think there should be proper solution for this.
namespace HelixUltimate\Framework\Platform\Classes;
defined('_JEXEC') or die();
/**
- 
Image manipulation class.
 
- 
 
- 
@since       1.0.0
*/
class Image
{
public static function createThumbs($src, $sizes, $folder, $base_name, $ext, $quality = 100)
{
         list($originalWidth, $originalHeight) = getimagesize($src);
         switch ($ext)
         {
                 case 'bmp':
                         $img = imagecreatefromwbmp($src);
                         break;
                 case 'gif':
                         $img = imagecreatefromgif($src);
                         break;
                 case 'jpg':
                         $img = imagecreatefromjpeg($src);
                         break;
                 case 'jpeg':
                         $img = imagecreatefromjpeg($src);
                         break;
                 case 'png':
                         $img = \imagecreatefrompng($src); <-- I changed this line. Added a \ in front of the function name. So the native function of GD is used
                         break;
         }