Admin manufacturer's list

Hi all

I have altered my shop to use authors instead of manufacturers. I have a large number of these. I have every thing sorted except one thing I want to do.
I would like the manufacturer/author image to appear on the front manufacturer/author list page so that I can se the image (if there is one) without going down a further level. So far I have created the column successfully but the heading of the column has this error:
Notice: Undefined variable: column_image in C:\xampp\htdocs\website\admin\view\template\catalog\manufacturer_list.tpl on line 91

90. <?php } else { ?>
91. <a href="<?php echo $sort_image; ?>"><?php echo $column_image; ?></a>
92. <?php } ?></td>

and the individual manufacture/author box in this column has this error:
Notice: Undefined index: image in C:\xampp\htdocs\website\admin\view\template\catalog\manufacturer_list.tpl on line 108
107. <td class="text-right"><?php echo $manufacturer['sort_order']; ?></td>
108 .<td class="text-right"><?php echo $manufacturer['image']; ?></td>
109 <td class="text-right"><a href="<?php echo $manufacturer['edit']; ?>" data-toggle="tooltip" title="<?php echo
$button_edit; ?>" class="btn btn-primary"><i class="fa fa-pencil"></i></a></td>

Where do I define the variable and undefined index?

Using Opencart 2.0.1.0

Any help appreciated

Subatwest