Watermarking: Image Protection on the Web

First, to identify yourself. This will allow viewers of your image, even when the image has been copied from the web site, to find their way back for purchasing quality versions of your image.
Second, marking your image can discourage inappropriate reuse of your image on the web.

File Format and Compression Quality:

The file size and format are the first line of defense in image protection. A size of approx. 400 pixels in the longest dimension for your image is good. This limits the ability to enlarge your image for print purpose. The format of your image is JPEG. This format sacrifices image quality for smaller image sizes. Compression causes the file to throw out some image data. Enlarging the image or printing the image (something an image pirate might try) brings out these defects more clearly than the computer monitor.

The JPEG format offers a sliding scale of image quality, generally presented as 1-10 or 1-100. Image quality and file size are reduced as the number gets smaller. Choosing level 5 (or 50) as your starting point for picking the right compression. This will usually give you good visuals on a computer screen, but begin to look bad when printed. Do not repeatedly open and edit a JPEG file, each time you save it the image is degraded. Plan to save a copy in JPG format as the last thing you do for web use.

Visual Marking:

Since we encourage visitors to use the visuals for project planning purposes (unless you state an image is not available for resale) it is likely they will get separated from the contact information on the web site. Visual watermarks can help your admirers find their way back to you as well as limit the use of your image. As image creators we want the viewer do see and appreciate what we have created. We have to make a balance between applying marks for protection, and not obscuring the art to an annoying extent. Below is a sample with several mark types:


Transparent text with drop shadow will stand out on different backgrounds. Its main purpose is to allow the viewer to find you again. By placing a permanent address on the image you can change your contact data any time at the Science-Art.com or Medical-Art.com web site and customers can still find you. A large transparent mark renders the image very difficult to reuse, but still allows the viewer to see the art. This one was created in PhotoShop 5.0 with the text tool and emboss effects. Any one color image can be used as a watermark. Place the image in a separate layer in PhotoShop and apply the emboss filter, then adjust the transparency of the layer and flatten the image. A straight ahead copyright notice at the bottom of your image can be used alone or in conjunction with mark one or mark two. It is easily removed and offers little useful information for contact. But it does show ownership. Cover the image area with a faint dropshadowed white text. This serves the double pourpose of making reuse difficult and idenifying the location of the image. In this case "SCIENCE-ART.COM."
You can use this Watermark Template Photoshop file as a starting point. The file is a compressed .zip file. Use a ZIP decompression utility or StufIt Expander to open the file. Photoshop may request that you pick different fonts if you do not have the ones defined in the template. When open, just drag the desired layers from the template into you image document. Use the shift key if you want the template layer centered in the new document.

Hidden Marking:

Hidden marking does little to protect your images from blatant theft; file size, file compression, and visual marks are the best defense for that. But they can be used as a contact method, and possibly hunt for stolen images on-line with automated software.

Hidden Watermarks:

The most common brand of watermarking software is Digimarc, it comes with PhotoShop. You can also download the plug-ins from the Digimarc web site and use them with other software that accept PhotoShop Plug-ins.

To use Digimarc, go to their web site and sign up for an ID number. This service now has an annual fee, even for the most basic account. Enter your contact information in their database and receive a Digimarc ID number and PIN number to verify you are using the right ID number; and pick a password so you can go back and edit your contact data at any time.

-Armed with these numbers you use the Embed Watermark plug-in to mark your image with a noise pattern that contains the ID number. This should be the last operation you do on your image before saving it for the web. The difficulty is the lossy nature of JPEG. It will also degrade the hidden watermark. Also it will only work on RGB images so the file format you will save is JPEG. The reader will show you the strength of the mark when you reopen you image file.

-When an image is opened in an image editor with the Read Watermark plug-in installed, the image window will show a copyright symbol. Selecting the Read Watermark filter will pop up a window with a direct link to the Digimarc web site where the viewer can check your contact information. A photoshop enhanced version of the image reveals the encoded noise which carries the ID information (lower right).

-If you care to pay Digimarc some more money, they will cruise the web with their automated software looking for pirated copies of your image. They also offer a free stand alone watermark reading program.

-Science-Art.com does not endorse or discourage the use of Digimarc products.

For a more complete discussion of image protection on the web check this overview: http://gnsi.science-art.com/2000PT/posters/griswold/