Mysterious padding in a table

I’m finding that table rows that I believe shouldn’t be adding anything into the table, are actually adding a row of pixels. I think I must be missing a tag (padding, spacing, border or something) but I just can’t find out what it is.

When I ask for the top offset position of this image, it increases by 1 for each empty row I have in the table before the row with the image in it:

<table border=0 cellpadding=0 cellspacing=0>
<tr><td></td></tr>
<tr><td>
<img src=“some-image-path.jpg”>
</td></tr>
</table>

I have a function that gets me the top offset of document.images[0] and with the above table, it’s one more than it should be. If I add another row (<tr><td></td></tr>) before the row the images is in, then I get yet another row of pixels.

I’m assuming there’s a tr or td property that I’m missing but all the info sites I look at don’t indicate one that I can see.