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Image Protection

Tips and Techniques to Protect Images on the Internet

written by Greg Cope

Protecting Images - Put plain and simple: the only way to protect your images from being downloaded or stolen off a web page is to not put them online in the first place. While I put this fact out there as blunt as possible, there are several techniques we can use to make website downloads and image theft much harder. Of course, image theft can be defined in a number of ways, and its definition - and hence measures (if any) taken to prevent it - will depend upon the individual.

There are many ways to protect images from being downloaded, ranging from modifying the image itself (tips 1-3), to preventing webpages downloads (tips 4-8), to being pro-active in finding unauthorized usage of images online (tips 9-10). And while I discuss many common types of image protection, there are many others that I do not mention. A few of the techniques mentioned in this article are directed more towards web designers (these tips are marked with an *), but several can be used on photo sharing website's such as smugmug, flickr, pbase, and webshots.

What is image theft? Image theft is the unauthorized use of an image, photograph, drawing, or illustration. Well duh. Is it really that simple? Of course not. The hard part is that many people differ in the definition of 'unauthorized use'. Where one person may not care whether their photograph is downloaded from a web page and placed on another website without their knowledge, there are some that find this to be blatant copyright infringement.

  • Can I download an image? If you are interested in knowing whether unauthorized downloading and use is illegal: many websites will have an image use statement, and it is best and safest to ALWAYS ask the artist for permission. Ultimately, the default for image downloading and usage should ALWAYS be "All Rights Reserved" (eg don't use without permission).
  • Can I protect an image? If you are an artist interested in protecting your images: it is best to first define for yourself what your policy on image theft is, then define the measures you need to protect your images (even if this means not putting your images online in the first place). It is important to publicly display your policy on image use in an image use statement on your website.
Image Protection - prevent image theft using a Copyright Watermark

"Protect images and pictures from theft by using watermarks.

1) Image Protection with a Watermark: The most common, and possibly strongest, image protection technique is to place a visual copyright watermark on the image. Image watermarks come in a range of styles: from a full copyright symbol across the image to simply small text in the corner of an image containing the copyright symbol, date, and name of the copyright holder. There is a trade off with watermark size: the larger the watermark the less likely one is to download or steal the image, but the larger the watermark the more of a visual distraction it becomes.

Image watermarks are easy to create in Photoshop: make a new layer with the desired text, adjusting its size and location to best suit your needs. To type the copyright symbol © in text, you can type option+g (mac) or Ctrl+Alt+C (PC). Changing the blending mode and opacity for this layer can create a more artistic and less obstructive watermark: for example 'soft light' layer blending can create a nice opaque blend. It is possible to further customize the watermark by using layer blending options such as a dropped shadow and/or beveling. Digimarc, a technology that can be integrated as a Photoshop plug-in, can also produce a digital watermark through the use of digital noise that is read by software. Despite the presence of a watermark however, its survival through image manipulations is not definite, and the lack of a visual symbol may not prevent image theft - only act as proof of copyright owner in case of theft.

Note: Of course an image watermark specifies a copyright directly in the image, but a copyright can also be clearly indicated in text near the image; including the date of copyright, the copyright holder's name, and your rights management (eg all rights reserved or a creative commons type license). For those that manage their own webpage, a copyright notice deserves special attention on its own webpage, indicating the copyright and your policy on image downloads, usage, and theft (see tip 10).

2) Image Protection Using Low Resolution: Low resolution images should almost always be used on the internet to protect them against theft. A 550 pixel (in its longest dimension) image saved at 72dpi is a good size for internet use, and will not give downloaders much image to work with: other than internet use, images of this size look quite horrible in just about any other application imaginable. On a photosharing site like flickr, images are resized down to 500 pixels (longest dimension) for basic viewing, thus you can upload images 500 pixels wide and not change how most view the photo.

3) A Note on Color Profiles: Much of the internet currently lacks color management (for more information see my article on Soft Proofing and Color Management for the internet). Uploading images without a color profile will not protect an image from being downloaded, but could potentially prevent it from being used: those wishing to use the image in a color managed, internet independent application may be at a loss if they see a drastic shift in colors and contrast and do not know how (or care to) to rectify it. For those that are worried about image quality due to a missing color profile, the consequences are small: the minority of viewers using color managed browsers will see exactly what those using non-color managed browsers see (if you ultimately wish viewers to see as close to what you see in photoshop, I recommend Soft Proofing your images for the web).

*4) Prevent Downloads Using Tables: 'Right clicking' images is a fast shortcut to find, copy, and/or download images. For those that have their own website it is possible to prevent this action by placing images as a background to tables. The code is fairly simple in CSS, using the "background-image:url" style:

<table style="background-image:url('image.jpg');width:Wpx;height:Hpx"><tr><td></td></tr></table>

no image protection
image protection using a table and transparent gif

The same image displayed using different image protection techniques. From left to right: the image displayed using the <img> tag, displaying the image as a background image to a table, and displaying the image as a background image to a table with an overlayed transparent gif.

The use of table backgrounds is demonstrated above. An additional modification, shown on the far right above, is to create a transparent .gif file and place this within the table data (<td>) cell itself - the result being right click downloads are still functional but the downloaded, copied, or viewed file is a transparent .gif.

Although time consuming, another method to protect images using tables is to section them, creating multiple images pasted together using an html table. To quarter an image in Photoshop create vertical and horizontal guides using View->New Guide. Each quarter can be copied (the View->Snap To->Guides should be checked to make selections easier) into new files. These images can the be re-assembled within a table without cellpadding or cellspacing (the 'vertical-align:bottom' style should be applied to the images). The result is a seamless image which takes a good deal of effort to re-assemble. Of course, this can be extremely time consuming (although the process can be simplified and automated using a short php script) and does not prevent print screen downloads. Further, small differences in browsers may ultimately result in small differences in how the table and image(s) are displayed.

*5) Javascript Right Click Disable: Another measure to prevent right clicks on images is to use Javascript. These short scripts over-ride browser right clicks. Rather than recreate a script that has been widely published in various forms over the internet, I will leave it to the reader to search google for Javascript Disable Right Click. I will however mention that Javascript is client-side, and scripts such as these can not only effect the usability of a website, but can also readily be disabled by turning Javascript off.

*6) Hiding Images: It is possible to look for an image by scouring the source code of a webpage in search of a link to the image. These links however, can be hidden in a number of ways by a web designer. First, they can be hidden within the code by url encoding: converting the html code of the image to ascii (hexadecimal). For example:

/dir/yourimage.jpg

~ versus ~

/%64%69%72/%79%6f%75%72%69%6d%61%67%65%2e%6a%70%67

Second, you can hide links to images in another file, making it harder to find with a simple "Show Page Source" command. For example, suppose an image is the background to table element (see tip 4). The "background-image" style can be defined in a class within an external CSS file and referenced in the table style. This makes finding the link to the image hard to find, especially if you have multiple CSS files linked through an html document. Further, for those experienced with server side scripting the CSS file can be written dynamically - overcoming the problem of having to write a CSS file per image, and making it once again harder to find as this file will usually not be named with a .css extension. Although it is possible to use a similar technique with Javascript, this approach can lead to unpredictable behavior because Javascript is client-side.

*7) Preventing Bandwidth Theft: Bandwidth theft, also known as hotlinking, is the process by which people use images from your server to display in their own webpages. The end result is that the image is still on your server but linked to and displayed by a remote website. It is incredible how easy this is to do and how often this occurs, and startling how many images found in image searches on google are hotlinked images. So why prevent hotlinking? There are a variety of reasons. As the name implies, other websites are stealing your bandwidth: in most cases the bandwidth is negligable, in a few cases it can add up. Further, when hotlinking occurs it is unknown in what context the image is being used. Lastly, the link to your website could be on a website that performs "black hat" or malicious activity.

Hotlinking is easily prevented however. Many hosting services provide a protocol by which to do this through their service control panel. Alternatively, the following lines can be placed in a website root directory '.htaccess' file. If you are unfamiliar '.htaccess' files, they are plain text files that allow you to make some powerful configuration changes on an apache server: I recommend reading the '.htaccess' tutorial at Apache, and being VERY careful when making changes to or overwriting them1.

RewriteEngine On

RewriteCond %{HTTP_REFERER} !^$

RewriteCond %{HTTP_REFERER} !^http://(www\.)?mydomainname\.com [NC]

RewriteRule \.(jpe?g|gif|bmp|png)$ - [F]

Of course, replace mydomainname with your domain name. If you wish to allow certain sites to hotlink to your images, for example website forums or search engines, you can add the following line before the RewriteRule line above, replacing 'externalsite' with the name of the website:

RewriteCond %{HTTP_REFERER} !^http://(www\.)?externalsite.com [NC]

When hotlinking is blocked, external links to images will turn into the dreaded image not found icon. This however can be changed to an image of choice by replacing the rewrite rule with the following:

RewriteRule \.(jpe?g|gif|bmp|png)$ http://www.yourdomain.com/dontlinktomyimage.jpg [NC,R,L]

-A note on hotlinking: when hotlinking is disabled using the above code, a 404 Not Found is recorded by your server each time the culprit webpage is loaded. On many servers these 404's can be accessed using webmaster tools. Alternatively, this information can be actively recorded using a custom 404 Not Found webpage that collects, through server side scripts, the information for you. Why collect this information? On many occasions, if the image cannot be hotlinked the culprit can simply find the image and host it themselves. Collecting this information gives you the ability to actively pursue potential image theft.

*8) Prevent Search Engine Indexing: Protecting images from search engine indexing can be accomplished in two ways. First, a META tag can prevent images from getting indexed, but allow the rest of the page to be found in searches:

<meta name="robots" content="noimageindex"></meta>

This meta information prevents search engine spyders (eg. robots) from indexing images only: this is in contrast to using the "noindex" or "nofollow" contents tags which are general commands that effect the entire webpage. The second method is to use a robot.txt file. This file, which should be a plain text file created with a simple text editor and placed in the root directory of a website, is inspected by search engine spyders the moment they arrive and is a method to tell spyders which directories or files on a website to NOT visit and NOT index. If you have a directory that contains all images for a website, this can be added to the file:

User-Agent:*

Disallow:/images/

Disallow:/image.jpg

The above example tells spyders or 'bots', designated by the asterisk, to disregard the directory /images/ and disregard the file /image.jpg. It should be noted that not all search engines honor these methods, and while major search engines such as google, yahoo, and msn honor them there will be other search engines that will not. Note: In the case of online photo sharing websites, flickr allows you to remove images from public searches: this is done within the Privacy and Permissions section of your account.

Sea Lion and Shark

One of my images that has been widely downloaded and placed on websites without my permission.

9) Finding Your Images: In the instance someone uses your image(s) without permission, you may usually never know. For online usage however, it is possible to be pro-active in finding unauthorized usage by simply searching for your images; the greatest tools being image search engines powered by google, yahoo, and MSN. Although this may seem like finding a needle in a haystack, at times it can be a very useful tool.

A very new tool on the scene of internet image search is a website tool called TinEye, designed by Idèe. Tineye is an image search engine using images rather than keywords to search the internet. Currently in beta testing, their search algorithm is quite impressive. However, their current index is far from complete and it is unknown whether their service will become freely available to everyone, or whether their services will come at a price.

In the case you end up finding unauthorized use of an image online and you wish to do something about it3, it is usually best to contact the webmaster(s) directly. If contact information is not provided on the webpage itself, resources such as WHOIS can be used to find technical contacts as well as hosting service contacts. Usually a simple email to the webmaster - stating the unauthorized use of your work and politely asking them to remove the image from their server - will do the trick. In certain situations a Cease and Desist letter may be necessary, specifying an infringement of copyright has been made as well as specifying your demands. Sometimes webmasters will be extremely cooperative. Other times not. In the event the webmaster does not comply with your demands, there are actions you can take, including a) Notifying their Advertisers b) Contacting the Hosting Service (found through a WHOIS) c) contact websites that link to the offending website asking for the removal of links2 d) send requests to search engines that the website contents be removed from their indexes. For a thorough discussion on stolen content and actions that can be taken, I highly recommend reading the following article: Stolen Content - How to Act.

Offline copyright infringement is a lot more difficult to detect. In either case, if you feel compensation is justified for copyright infringement, I suggest contacting a copyright attorney to discuss your options3.

10) Copyright Images3: A copyright is a form of protection provided by law that prevents the use of a piece of work, and the copyright owner the person who originally created that work (please visit the United States Copyright Office for more information). In almost every case, if you push the shutter button you hold the copyright. However, it is always advisable to register a copyright of your images with the United States Library of Congress or a similar entity in the country where you reside. While this will not prevent images from being downloaded and/or stolen, it will give you proof that you are the copyright owner. Registering is easy, cheap, and can be done in batch (eg you can register several images, such as "Photographic Works of - First Quarter, 2008").

There is no international copyright law which provides immediate protection for an artist against unauthorized usage: however most countries have copyright laws that pertain in that country. Protection is also provided internationally through the Berne Union for the Protection of Literary and Artistic Property (Berne Convention) and the Universal Copyright Convention (UCC). For more information on international copyright laws, the US Copyright Office has a circulation article available as a PDF on International Copyright policies.

Image Protection - Conclusions

Every image protection technique will have its pros and cons. A watermark can detour image theft but can also be considered unsightly. A low resolution image can prevent theft because of the quality - but because of the quality effect what the image portrays. Preventing right click can prevent direct downloads but does not prevent 'screen dumps'. However, the combination of techniques can become powerful in discouraging unauthorized image usage.

Will there ever be a solution to online image theft? In a naive sense we all would like to think so, but in all honesty doubt it. Watermarks can be edited, and regardless of how well the URL to an image is hidden, people always have the 'print screen' option. However, in my experiences in having my images used without my permission (at least those that I am aware of), many of the people doing so had little knowledge that they were guilty of copyright infringement - so perhaps education about copyright infringement and image theft is part of the solution.

What I do: Finally, you may be wondering what I do for image protection. All my images are registered with the Library of Congress, I prevent hotlinking, my images lack color profiles, are low resolution, and a few may have various copyright watermarks. Occasionally, whether out of curiosity or paranoia, I will do an image search for my images. That being said over the course of time I have used almost every one of the preventative steps above during various stages of paranoia. While some of the techniques have stuck, others have not. I have found many of my images placed on other websites, and have sent out a fair share of letters to webmasters. So what measures should you take for image protection? Ultimately it comes down to doing what you feel appropriate to protect your images, even if that means not putting them online in the first place.

For questions or comments on this article, please contact Greg Cope.

Other Resources on Image Protection:

US Library of Congress - United States Copyright office for copyright registration.

Stolen Content - Content protection and what to do in case of theft.

Creative Commons - Non-profit organization providing creative licenses for image works.

Content Theft - The growing trend with websites and blogs.

1Greg Cope and Nature Focused accept no responsibility in the event of losses or changes to the configuration of a webpage due to the addition or modification of the .htaccess file.

2While it can be difficult to find all external links, Yahoo provides one of the more thorough link finders: go to Yahoo search and enter "linkdomain:www.thedomain.com". Links can also be found in google using "link:www.thedomain.com", although they may not be as comprehensive.

3Please note this is provided as an informational resource only. I am not a lawyer. I cannot advise people with regards to copyright infringement. Further, I accept no responsibility for anything as a result of this article.