Stop table cell from adapting to true image size

It's interesting how a table cell won't adapt to your resized image when you resize it by percentages. If you resize it with absolute values, it does the job.

Is there any solution to this?

Let's say we have an img with 200px width.

Now, 2 code scenarios.

First:

<td><img src="..." style="width: 50%; height: auto;" /></td>

Second:

<td><img src="..." style="width: 100px; height: auto;" /></td>

I would assume in both cases it will look the same, but it doesn't. In the first case the td still has a width of 200px. Only in the second case the td resizes to 100px width.

Percentual resizing is very important to me though. Is there any css trick for this problem?