Well, it is so sad to say that there is no way to protect the images from being copied until the time of writing this post. You may probably tell me that you found a lot of “Image Protection” tools on web. Yeah. I know. I did even tried some of them once. Those tools make people difficult to copy the images from your website. but there are always some sort of hecks for copying images. No matter what tools or technologies you use.
I will tell some attempts that people tried to achieve this goal and the reason why those attempts were failed.
This is very very old trick and it’s totally useless. Don’t forget “Save As” in File menu. Plus, there are a lot of DOM manipulators (eg: Firebug) to track the path of images.
#2. Adding new transparent image over the actual image
I found some sites (including flickr) that are using this technique to protect their images from being copied. It works for normal users who only knows “Right Click” and “Save Image As”. You can still check the source to get the correct path of actual image that you want. If you are familiar with firebug, you can easily delete the transparent image that you don’t want on the fly.
#3. Using third-part tools for image protection
If you do googling about this a lit bit, you will get a ton of tools advertising that those tools will help you to protect your image from being copied (some even said that those tools are able to protect HTML code too.) Don’t even never spend your money on those tools. I mean it. As I said above, I tried already. I know those tools are not good enough since they have their own limitations. So, don’t waste your money on it.
This fact applied for code protection tool also. Those tools are going to encrypt your webpage and will add a lot of whitespace in your actual source. So, if you check the “View Source” a lit in your browser, you will see plain text or some text you write instead of HTML code. but don’t forget to scroll a lit bit.. You will see goddammed things.. and those tools will eat your bandwidth and it made your visitors to view the web page in slow motion. :)
#4. Putting images in Embedded Object (Flash or ActiveX Object)
I think this is the best way to protect the image so far. but it is possible to download the whole flash file (*.flv) to local machine by using third-party tool or firefox extensions (eg: Download Helper). So, the individual image are safe from being copied but not for flash.
UPDATED (27th August, 2007):
Watermarking (Thanks to mmhan for reminding me about this.)
AFAIK, there are two ways of watermarking. The first way is that putting a watermark simply on the image. This watermark will be visible to everybody. The second way is that putting a invisible watermark on the image by using Steganography.
Yeah. those are the ways that I remember how people tried to protect their images. If you have other ways, don’t hesitate to let me know.
Remember! All images from the webpage are already sent to the temporary internet files of user’s local machine before showing to the web browser. So, user can still copying images from Temporary Internet File folder. And, What about “Print Screen”? :)
So, if you ask me how to protect the image, I would say “don’t do that!” . :)