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Last update: 09-12-2005
Contributed by Steve

"I moderate several large discussion lists, and a topic that often draws a lot of heat is whether it is possible to truly protect your images from thieves. This is an important, yet misunderstood, topic. With appropriate determination, there is nothing web developers can do to prevent images from being swiped. In this article, I will tell you why."

Keeping your graphics safe online

I moderate several large discussion lists, and a topic that often draws a lot of heat is whether it is possible to truly protect your images from thieves. This is an important, yet misunderstood, topic. With appropriate determination, there is nothing web developers can do to prevent images from being swiped. In this article, I will tell you why.

How downloading works

To understand why image protection on the web is nearly impossible, it is prudent to first discuss how downloading works. When you visit a web site, the content, which includes the web page itself, graphics, javascripts and other page elements are downloaded to your hard drive (cache). Then, the browser retrieves the page's elements from the cache and displays the complete page.

This is so important that it bears repeating. Each time your visitor views your site, your graphics are automatically downloaded to their computer system. This, in and of itself, is not stealing. Your graphics only become stolen when and if the viewer uses your content in other ways, like on their own web page.

To steal a graphic, all the user needs to do is locate the folder that the browser uses for cache and copy the image. While this process may not be apparent to novice users, many failed techniques that some web developers use to prevent this "theft" are. Next, let's discuss these techniques and the merits and limitations that each present.

Techniques to prevent image theft

Remember that image theft cannot be prevented. Below, let's kick around some techniques that web developers use to help prevent more novice users from stealing graphic files.

No-right-click scripts: Javascripts exist that will prevent the ability to right click on a web page. These scripts are installed in an effort to prevent a user from right clicking on a graphic file and selecting 'Save Image As'. Unfortunately, this method should be avoided at all costs.

Right clicking is a well used computer utility, one that many users are familiar with and have grown to depend on. The ability to right click provides more functionality than just 'Save Image As', or 'View Source'. It also allows users to go back a page, or reload or print a document. By disabling right clicking, you also disable these entirely legitimate functions that some users rely on.

Disabling the right click function is simply unprofessional. It means that you don't trust your users and generalize their appetite for theft. More importantly, it offends some users and may lead to lost business.

Added, because Javascript is interpreted on the client side (by the user's browser), it can be disabled by the user. Browsers offer the ability to disable the execution of Javascripts, which means the code used to prevent right clicking will not get executed. Thus, in addition to it being unprofessional, it is entirely inconsistent and wholly unreliable.
Watermarks: Placing light colored text across the middle of your photo gallery images is a far better way to prevent image theft. While it doesn't prevent the image from being downloaded to the viewer's cache, it does make it all but useless for anyone else to use.

Or course, watermarking your images does come at a price. Displaying text across the middle of the image may lessen its quality and annoy your legitimate users. Before watermarking your images, weigh the risks in your own situation.

Digital watermark technology exists from a company called Digimarc. This technology embeds tiny bits of identifiable information in your graphics. While this will not prevent your graphics from being stolen, it does provide you with an interesting way to track where your images are being used.
Small image size: Displaying only low quality versions of your graphics is conceptually similar to the watermark technique. In effect, this may discourage other users from stealing your graphics if the quality is low enough. Other users may find the graphic fairly unusable as a result and will pass on trying to steal your images.
Flash/Java applets: Both Flash and Java applets present another way for web developers to prevent the easy theft of their images. The Washington Post web site, for example, uses Flash technology to display a slide show of the day's photographs, and it works well. Although the Flash file is downloaded to the user's computer, only a skilled Flash user will know how to extract the individual graphics. Thus, using Flash or Java applets will only prevent more novice users from stealing your images. If you do decide to use this method, use Flash instead of Java applets because it will download and display faster.
Transparent GIF: This technique involves placing a transparent GIF layer directly over the image. When the user right clicks on the graphic, they can only directly save the transparent GIF file, not the underlying image. This has virtually unlimited potential to confuse the heck out of your web users.
Source code encryption: Software exists that will jumble up your HTML source code, making it effectively unreadable by curious web users. This may prevent the user from inspecting your source code to find the location of where your images are saved. Keep in mind that if your web users are experienced enough to read through HTML and find image locations, they may also be experienced enough to try other techniques that work better, which makes this method unhelpful.

Screen shots destroy all techniques

None of the methods described above will prevent a user from capturing a screen shot of your web page (Print Screen key). After the capture, all the viewer needs to do is bring the graphic into a program like Adobe Photoshop or Macromedia Fireworks and extract the graphic (or Flash/Java applet image). While novice users may not be aware of this method, or possess the ability to perform it, it does present a pretty simple way for users to steal your graphics. In fact, some users may be determined enough to take a digital picture of their computer screen, showing your web page, with a digital camera. Strange, but true.

There is a company called Artistscope that claims to be able to disable screen shots, but that requires that all users download a particular plugin, which creates hassles for users. Web surfers are impatient and want content quickly and easily. Do not require them to download additional plugins before viewing your content.

Okay, so what is the bottom line?

First, come to grips with the fact that you cannot prevent your graphics from being stolen by determined thieves. While methods exist that keep novice users from the crime, it may disable otherwise legitimate functionality or introduce unnecessary complications or annoyances.

The bottom line is do not look to technology to protect your images. Rather, web developers need to make their graphics useless to other users. This does include the use of watermarks or low quality graphics, especially on photo gallery graphics. Watermarks discourage users from stealing and reusing your graphics because the evidence of theft is clearly in sight. If you feel strongly enough about protecting your graphics from theft, and require 100% protection, your only recourse is to keep them off the Internet.

Author: Steve