Upload med watermark

hej jeg er igang med at lave et upload til profilbillede
men jeg vil gerne vide hvordan man ændre navn på det billede
som er er kommet mit icon
mit script ser så ledes ud og virker.

 <?php
   //--------------------------------
   // CREATE WATERMARK FUNCTION
   //--------------------------------
 
   define( 'WATERMARK_OVERLAY_IMAGE', 'watermark.png' );
   define( 'WATERMARK_OVERLAY_OPACITY', 50 );
   define( 'WATERMARK_OUTPUT_QUALITY', 90 );
 
   function create_watermark( $source_file_path, $output_file_path )
   {
     list( $source_width, $source_height, $source_type ) = getimagesize( $source_file_path );
 
     if ( $source_type === NULL )
     {
       return false;
     }
 
     switch ( $source_type )
     {
       case IMAGETYPE_GIF:
         $source_gd_image = imagecreatefromgif( $source_file_path );
         break;
       case IMAGETYPE_JPEG:
         $source_gd_image = imagecreatefromjpeg( $source_file_path );
         break;
       case IMAGETYPE_PNG:
         $source_gd_image = imagecreatefrompng( $source_file_path );
         break;
       default:
         return false;
     }
 
     $overlay_gd_image = imagecreatefrompng( WATERMARK_OVERLAY_IMAGE );
     $overlay_width = imagesx( $overlay_gd_image );
     $overlay_height = imagesy( $overlay_gd_image );
 
     imagecopymerge(
       $source_gd_image,
       $overlay_gd_image,
       $source_width - $overlay_width,
       $source_height - $overlay_height,
       0,
       0,
       $overlay_width,
       $overlay_height,
       WATERMARK_OVERLAY_OPACITY
     );
 
     imagejpeg( $source_gd_image, $output_file_path, WATERMARK_OUTPUT_QUALITY );
 
     imagedestroy( $source_gd_image );
     imagedestroy( $overlay_gd_image );
   }
 
   //--------------------------------
   // FILE PROCESSING FUNCTION
   //--------------------------------
 
   define( 'UPLOADED_IMAGE_DESTINATION', 'originals/' );
   define( 'PROCESSED_IMAGE_DESTINATION', 'images/' );
 
   function process_image_upload( $Field )
   {
     $temp_file_path = $_FILES[ $Field ][ 'tmp_name' ];
     $temp_file_name = $_FILES[ $Field ][ 'name' ];
 
     list( , , $temp_type ) = getimagesize( $temp_file_path );
 
     if ( $temp_type === NULL )
     {
       return false;
     }
 
     switch ( $temp_type )
     {
       case IMAGETYPE_GIF:
         break;
       case IMAGETYPE_JPEG:
         break;
       case IMAGETYPE_PNG:
         break;
       default:
         return false;
     }
 
     $uploaded_file_path = UPLOADED_IMAGE_DESTINATION . $temp_file_name;
     $processed_file_path = PROCESSED_IMAGE_DESTINATION . preg_replace( '/\\.[^\\.]+$/', '.jpg', $temp_file_name );
 
     move_uploaded_file( $temp_file_path, $uploaded_file_path );
 
     $result = create_watermark( $uploaded_file_path, $processed_file_path );
 
     if ( $result === false )
     {
       return false;
     }
     else
     {
       return array( $uploaded_file_path, $processed_file_path );
     }
   }
 
   //--------------------------------
   // END OF FUNCTIONS
   //--------------------------------
 
   $result = process_image_upload( 'File1' );
 
   if ( $result === false )
   {
 
     echo '<br>An error occurred during file processing.';
   }
   else
   {
     echo '<br>Original image saved as <a href="' . $result[ 0 ] . '" target="_blank">' . $result[ 0 ] . '</a>';
     echo '<br>Watermarked image saved as <a href="' . $result[ 1 ] . '" target="_blank">' . $result[ 1 ] . '</a>';
   }
 ?>

men jeg vil gerne lave mit navn om på det billede som bliver watermarked