I have tried the following ways without result ...
... in the body of the table
<tbody background="./images/credibanco.jpg" style="background-repeat: no-repeat; background-position: center center;">
<?php
require_once '../ConsultasSW/ConsolidadoOperacionClientesSW.php';
echo ConsolidadoOperacionClientes($_POST["v1"], $_POST['v3'], $_POST['v4']);
?>
on the div that contains the table
<div id="operacionClientes" style="background-image: url(./images/credibanco.jpg)">
<table id="opeClientes" class="display nowrap" cellspacing="0" width="100%" style="text-transform: uppercase; font-size: 11px; text-align: center;">
<thead>
<tr>
<th>Cantidad de productos</th>
<th>Valor total</th>
<th>Tipo de entrega</th>
</tr>
</thead>
<tfoot>
<tr>
<th>Cantidad de productos</th>
<th>Valor total</th>
<th>Tipo de entrega</th>
</tr>
</tfoot>
<tbody>
<?php
require_once '../ConsultasSW/ConsolidadoOperacionClientesSW.php';
echo ConsolidadoOperacionClientes($_POST["v1"], $_POST['v3'], $_POST['v4']);
?>
</tbody>
</table>
but I did not manage to get it, what I need is that the image is in the background in the watermark table so that it does not become complicated to understand the contents of the table ...