when changing image-size td-size won't change - html

Question

I have made a table with three columns, two with text and one with a picture. The table has 10 rows, so I gave the the cell with the picture a rowspan of 10. I am able to change the width of the picture, but for some odd reason the table-cell won't change it's width. The cell still have the width, the picture originally had.
I have tried setting the image to block, but that doesn't help with the td-width. I could give the td a class with a max-width, but I am looking for another solution.
example
HTML
<table>
<thead>
<tr><th colspan="2">Attribute</th></tr>
</thead>
<tbody>
<tr>
<td>Stufe</td>
<td>9</td>
<td rowspan="10"><img src="#"></img></td>
</tr>
<tr>
<td>Vitalität</td>
<td>12</td>
</tr>
<tr>
<td>Zauberei</td>
<td>10</td>
</tr>
<tr>
<td>Kondition</td>
<td>11</td>
</tr>
<tr>
<td>Belastung</td>
<td>15</td>
</tr>
<tr>
<td>Stärke</td>
<td>13</td>
</tr>
<tr>
<td>Geschicklichkeit</td>
<td>12</td>
</tr>
<tr>
<td>Intelligenz</td>
<td>9</td>
</tr>
<tr>
<td>Glaube</td>
<td>9</td>
</tr>
<tr>
<td>Glück</td>
<td>7</td>
</tr>
</tbody>
</table>
CSS (nothing special)
table {
font-size:90%;
margin:1.5em auto;
padding:0 1em;
border-collapse:collapse;
text-align:center;}
article table thead {
background:#91414B;}
article table th, main article table td {
padding:0.25em 0.5em;}
table img {
display:block;
width:50%;}
table a {
text-decoration:underline;
color:#FFFFFF;}
table a:hover {
text-decoration:none;
color:#C6C6C6;}