I understand that you can do the following to generally prevent images or pages from getting indexed.
Add to the page's meta section:
<meta name="robots" content="noindex" />
Edit the robots.txt file:
User-agent: *
Disallow: /images/
User-agent: *
Disallow: /$folder/whatever.jpg
User-agent: *
Disallow: /$folder/*.gif$
User-agent: Googlebot-Image
Disallow: /$folder/*.gif$
Say you have a page which is indexed and you have an image referenced in a stylesheet (background image, whatever) or an image in an ordinary img tag,
<img src="/$folder/img.gif" alt="whatever title="yadda" />
So, according to the robots.txt the folder or specific image should not be indexed, however, the page is indexed (no no-index).
Will the search engines, in specific Googlebot-Image, honor the request? Index the page to the exclusion of the image in an img tag?
Will it also honor the request with regard to styled background images?