Image size relative to columns?

I can specify the pixel width of images using MMD syntax, as explained in this post: … 69&start=0

When I don’t, the latex that comes out specifies the image width in “\textwidth”. I’ve found that for some reason, the template I’m using gives a bad value for this, so that the image spills over into an adjacent column (or goes off the page if it’s in the right column). Is there a way to pass in “width=\linewidth” instead of ‘width=200pt’?

EDIT: Alternately, is there a way to tell MMD to use the *'d figure syntax, as in:

\begin{figure*} … \end{figure*}

I’d actually like some images to span both columns so that I can see more detail.