Views Output Field as Link: Change link text
While editing your view, open the field you want to modify.  In your case it would be your Image field that current output's &lt;a href='...'&gt;Download&lt;/a&gt;

Scroll to 'Rewrite Results' and check the box next to 'Rewrite the output of this field.'

Enter the text that you would like to display instead of 'Download.'

I believe if you use the Tokens module, you will have several variables accessible to you as well.  See "Replacement Patterns" in the same menu to see what is available.