We ran posts by Jeff Wignall  and Tony Blei  last week describing two ways to protect your copyrighted images. But while it’s valuable to understand your recourse under the law, it can be just as useful to know how to use technology to protect your content.
In fact, in some instances, technology may be your only real option.
Hotlinking and the Law
Take, for example, the case of hotlinking. Hotlinking is when another Web site displays an image on its site by pulling the image from your server. The most widely accepted example of hotlinking is what Google does when it displays thumbnail images in its search results. These images aren’t stored on Google’s servers; they are stored on the sites that host the images.
It’s very easy for any Web site to hotlink to the images on your site. And as the courts have ruled in Google’s case, hotlinking is judged more favorably under copyright law than the uploading of a photo onto an infringing server.
In the 2007 case of Perfect 10, Inc. v. Amazon.com, Inc., the U.S. Court of Appeals for the Ninth Circuit ruled that hotlinking (“in-line linking”) as used by Google did not violate copyright law. Specifically, the court stated:
Because Google’s computers do not store the photographic images, Google does not have a copy of the images for purposes of the Copyright Act. In other words, Google does not have any “material objects…in which a work is fixed…and from which the work can be perceived, reproduced, or otherwise communicated” and thus cannot communicate a copy. Instead of communicating a copy of the image, Google provides HTML instructions that direct a user’s browser to a website publisher’s computer that stores the full-size photographic image.
Providing these HTML instructions is not equivalent to showing a copy. First, the HTML instructions are lines of text, not a photographic image. Second, HTML instructions do not themselves cause infringing images to appear on the user’s computer screen. The HTML merely gives the address of the image to the user’s browser. The browser then interacts with the computer that stores the infringing image. It is this interaction that causes an infringing image to appear on the user’s computer screen.
Hotlinking doesn’t have to result in a thumbnail image; it can display as a full-size image as well. If you have a photography blog with an RSS feed that displays your images, it’s a simple matter for any Web site to pull that entire feed, images and all, onto its site without ever hosting one of your images on its own server. And it uses your bandwidth every time a site visitor calls up one of your images.
Hotlinking is not a bad thing in and of itself. If the Web site that hotlinks to you also gives you credit for the image and links back to your site so that new visitors can find you, it can be well worth the tradeoff, particularly because bandwidth is so inexpensive.
But if you don’t want sites to hotlink to you — or you don’t want certain sites to hotlink to you — your simplest and most effective recourse is not the law. It’s to change the code on your site to block offenders.
One way to ban hotlinkers is to use the Apache distributed configuration file called “.htaccess”. While it doesn’t work for all sites, it does work for most. Apache is the most popular Web site server, serving more than 100 million sites. (If your site is not on an Apache server or you do not self-host your site, check with your provider for options to block hotlinks.)
Jonathan Bailey at Plagiarism Today  says blocking hotlinks is “one of the easiest and most basic tasks that can be performed with .htaccess.” It can be used to ban all hotlinkers, ban specific hotlinkers, or to send an alternate image (imagine the possibilities!) to offending sites. You can find instructions for adding an .htaccess file to your site here , and get help with configuring your .htaccess file here .
You can also use .htaccess to block sites from “scraping” your site’s RSS feed — basically, taking your feed and then displaying it, in all or in part, on their site.
Feedburner and Flickr
Unfortunately, you can only use .htaccess for images and feeds hosted on your own server. Feeds hosted by Feedburner and images hosted by Flickr are another story.
Feedburner enables you to see “uncommon uses” of your feed content, which can help you to identify image thieves, but it won’t block their ability to receive content. Here’s Feedburner’s advice :
You may ask what you can do if you see a domain using your feed in a way that you feel is not appropriate (e.g., the feed content is posted on the site without proper credit to the source of the material). In this case, you should contact the domain or the domain host and take up the issue with them directly. You may also want to use the FeedBurner Creative Commons Service (on the Optimize tab) which adds a machine-readable Creative Commons copyright license to your feed.
The same kind of limitation applies when you host images on Flickr or other photo-sharing services. With Flickr, you can identify the sites that are accessing your images, but the only way to block them is to make the images “private,” which blocks virtually all visitors.
So in these cases, you’re back to contacting copyright violators directly and pursuing the legal path.
In addition to contacting the offending Web site, it’s also a good idea to report the site  that is using your images to Google and to other search engines . The search engines may respond by no longer indexing or hosting advertising on the site, putting a serious damper on its ability to make money from your content.