如何使用php在条形码中显示表格数据

Question

我希望在条形码图像中显示我的mysql表数据字段

<table style="border:none" width="540">
    <tr>
    <?php 
    $exam_fee_stud_regular_subject_query = $mysqli->query("SELECT * FROM student_master") 
        or die($mysqli->error.__LINE__);

    while($exam_fee_stud_regular_subject_row = $exam_fee_stud_regular_subject_query->fetch_array()) { 
    ?>
      <tr>
        <td align='center' width="50">
          <?php echo $exam_fee_stud_regular_subject_row['rollno']; ?>
        </td>
        <td align='center' width="50">
          <?php echo $exam_fee_stud_regular_subject_row['stud_name']; ?>
        </td>
      </tr>
    <?php 
    } 
    ?>
</table>

我想在条形码中显示rollno