How to print a field value in page front tpl file?
I am not sure if this is what you are asking for, I think you want to show a download link for an image on your home, you have image on your node with node id 3.

In this case you can use download_file module, it allows to create direct download link for fils/images.All you need to do is create a view(through views module) of display type block, in your view add image field and keep the formatter as direct download file, place this block on front page.

If you want to render the download link programmatically, you can use the same function as defined in download_file module to render the links.

If you want to print image programmatically consider this:

print theme('image_style', array('path' =&gt; $node-&gt;field_theme_image[$node-&gt;language][0]['uri'], 'style_name' =&gt; 'home_theme'));