Photoshop :: Can't Make Illustrator Export Design With Correct Image Size

I have a designer that created this beautiful (but complicated) design in illustrator and now we're trying to get it exported to html. The thing is, most of the images that are in tds we want to be background images so that we can put stuff on top of it. So we need the exported html to generate the image size correctly. For example, I don't want

<img src="someimage.jpg" width="100" height="100"...

but

<img src="someimage.jpg">

The problem is that illustrator for whatever reason is generating the images slightly too small (I guess to make the image size smaller?), then is stretching them using width and height attributes. As I'm sure you guys are aware of, the background attribute has no way of specifying a width and height.