I have changed the cell render in JTable to show image instead of text using the following code:
base_table.getColumnModel().getColumn(3).setCel
The data stored in a JTable can be found in its TableModel. But since it's your code, normally, that builds this TableModel (from a list or an array, typically), you should be able to get the icon from this list or array. Else, just use table.getModel().getValueAt(row, column), and cast it to an ImageIcon.