You’ve likely heard of using robots.txt to ensure search engines don’t index the contents of your site (or specific pages within your site), but you might not know that this tag within your html is not enough to prevent search engines from indexing the images on your site.
Recently, one of the dev websites for a site we maintain experienced their images appearing in search engine photo results despite our use of robots.txt to block all search engines spidering the site. Searching for a cause, we discovered that in order to prevent images from being indexed by search engines, an image robots tag must be included.
Setting up an image robots tag is as simple as adding the following code to the page with the images you don't want indexed. This must be placed in the page's head section:
<meta name="robots" content="noimageindex">
Note however that if someone has linked to your image or if the image’s filename includes keywords, search engines may still index the images, even with the above tag.
Image robot crawls occur at least once every 90 days so keep in mind that the effect of these changes will not be instantaneous.
Photo courtesy of Shiny Things on flickr
