Qt: Space between individual cells in QTableWidget

(Using Qt 5.5.1 on Windows 8.1)

I have a table displaying images selected by the user.

I know their are many other ways to display multiple images on a GUI, but I'm new to Qt, so I didn't understand how to use QGraphicsView and found the following to be the easiest way.

But this forms a table in which images are not separated. I want some space b/w them. See how the next images starts right where the first ends.

Attachment 11684

How can I do it so that next image starts after leaving some space?

Code:

QFileDialog dialog(this);
dialog.setNameFilter(tr("Images (*.jpg)"));
dialog.setFileMode(QFileDialog::ExistingFiles);
QStringList all_filenames = dialog.selectedFiles();
int maxCol    = 3;                         
int maxRows   = all_filenames.size() / maxCol;
ui->tableWidget->setColumnCount(maxCol);
ui->tableWidget->setRowCount(maxRows);
int remainder = all_filenames.size() % maxCol;
if (remainder != 0)
{
   maxRows +=1;
}
ui->tableWidget->horizontalHeader()->setDefaultSectionSize(200);
ui->tableWidget->verticalHeader()->setDefaultSectionSize(200);
if(all_filenames.isEmpty() == 0)
{
 for( int i = 0; i < all_filenames.size() ; ++i)
  {
      QPixmap map(all_filenames.at(i));
      map = map.scaled(200,200,Qt::IgnoreAspectRatio,Q::FastTransformation);
      QBrush brush(map);
      QTableWidgetItem* item = new QTableWidgetItem();
      item->setCheckState(Qt::CheckState());
      item->setBackground(brush);
      ui->tableWidget->setItem(j,k,item);
      k++;
      if ( k == maxCol )
      {
          j++;
          k = 0;
      }
 
 
  }
}