Do search engines treat the alt text of an image placed within an h1 tag the same way they would treat regular text placed in an h1 tag?

I gave a search through here looking for an answer to this question, but was only able to find information on image replacement and the infamous h1 debate.

For example would:

<h1><img src="#" alt="Contact Us" /></h1>

Act the same as:

<h1>Contact Us</h1>

In the electronic eye of a search engine?

This seems considerably less "CSS Hacky" than other image replacement techniques like negative text indents, display:none, height:0, or ridiculous z-index integers.