What is a Digimarc-enhanced image?

It’s an image that contains a hidden message. That embedded message gives the image powerful new roles in the areas of tracking, Internet marketing, asset management and copyright communication. The hidden message in a Digimarc-enhanced image is imperceptible under normal use, yet easily detectable by software and other devices. The message contains a small amount of digital information, carrying attributes and a set of unique IDs.

Why you should use Digimarc-enhanced images

Anyone who licenses or publishes images, or uses them in a marketing campaign, can benefit from Digimarc-enhanced images. A national museum currently uses them to communicate ownership of its often-copied artwork. A record company tracks the use of its musicians’ photographs throughout the Internet. A major stock photo agency embeds its company name and contact information into its digital photos. These Digimarc-enhanced images serve as “mini-ads” for the company.

What they can do

At the most basic level, a Digimarc-enhanced image is “marked” as uniquely yours. The embedded message tells the world that you own the image’s copyright. But Digimarc-enhanced images are also “smart images.” Their special embedded message actually allows them to do things.

Digimarc-enhanced images can:

  • Help you find your images, wherever they go: Digimarc-enhanced images become homing beacons on the World Wide Web. They allow you to track where and when your images have been moved or copied.
  • Take you places: More than just a hyperlink, Digimarc-enhanced images can take viewers to a web site, a licensing data base, an image archive, an internal asset management system, and much more.
  • Instruct software and hardware: Digimarc-enhanced images can invoke copy protection (in video, for example) and other automatic responses.
  • Announce your copyright, as previously described.

In addition to all that, despite their embedded messages, Digimarc-enhanced images look untouched. This is because the hidden message is buried subtly in the image’s pixels. At very high magnification, the message appears as a slight change in the image’s grain or texture.

How to start using Digimarc-enhanced images

First you register with Digimarc to receive your unique Digimarc ID. This ID links your images to a contact profile in Digimarc’s database or to an Internet destination. You then embed Digimarc messages with your ID into your images, transforming them into Digimarc-enhanced images.

From there, you publish your Digimarc-enhanced images just like regular images. Viewers who see your images can use a widely available Digimarc reader to detect and interact with them. The good news is that millions of people can already interact with a Digimarc-enhanced image, since a Digimarc reader is available at no charge on the Digimarc web site.

It’s even possible to interact with Digimarc-enhanced images directly through a Web browser. Using Digimarc Mariner, users can turn images into visual bookmarks and explore the smart features of Digimarc-enhanced images. No matter where the images are published, a single click can take the viewer of your Digimarc-enhanced images to information related to them. Digimarc can also help you track the use of your Digimarc-enhanced images on the web with the MarcSpider service.

How Digimarc-enhanced images work

Digimarc-enhanced images are “smart” because of what’s inside them. Each Digimarc-enhanced image carries a digital message that is imperceptible under normal use, but detectable by computers and software. Digimarc’s technology embeds the message by making subtle changes to the brightness of the pixels in an image. Because the embedded message is carried by the image’s pixels, it is independent of the file’s format. It can survive normal image edits, file format transformations, copying, printing and scanning.

Inside information

The message embedded in a Digimarc-enhanced image carries identifying information, attributes or instructions. In Digimarc’s Internet imaging system (used for copyright communication, asset management and marketing & e-commerce), a unique Digimarc ID; an image ID, transaction ID or copyright year; and a set of image attributes is embedded. This information links to places and information, uniquely identifies the image, and communicates information about the image to applications.

Repeated for robustness

One of the patented features of a Digimarc-embedded message is that the pattern containing the message is repeated over and over throughout the entire image. This repetition strengthens the message so it can be recovered even after the image is cropped or otherwise changed.

While pattern repetition provides part of the durability solution, Digimarc-enhanced images must also survive more radical transformations such as scaling and rotation. To address this need, Digimarc created a patented technique that adds a hidden “orientation pattern” to the image. Using this special feature, Digimarc’s reader can recover the watermark after scale changes of as much as .6 times to 2 times the original image size. A Digimarc watermark can also survive any amount of image rotation.

These features are important for watermarks to be able to survive changes from a digital to an analog format and back again. Examples include outputting a digital image to print, then scanning it back into digital form; or recording a digital video to VHS format and then back to digital form.

Striking a balance

All of this work necessitates an important balance. Clearly the increased functionality provided by the embedded message is of great value, but the image itself must always be the main consideration. While the embedded message must be sufficiently robust to withstand the expected image modifications, it must also remain imperceptible under normal use. That’s why another of Digimarc’s patented innovations is the ability to make Digimarc messages “perceptually adaptive.” They conform to the unique pattern of each image, placing more energy in areas with rich detail and less energy in flat areas. This process ensures that Digimarc messages remain durable without being easily visible.

Notes on durability, quality and compression

While Image Optimizer automates the embedding process as much as possible for you, you will still need to make decisions concerning message intensity, durability, image quality and compression level. It’s important to remember that each of these elements affects the others.

When compressing a batch of images, you can instruct Image Optimizer to determine whether or not the message has been successfully embedded by measuring its durability, which can be thought of as the ability of the message to survive image modifications such as cropping, scaling, rotating, etc. If Image Optimizer finds that an embedded message has an unacceptable durability, it embeds the message again at a higher intensity. Intensity is the amount of energy that is applied in embedding the message; in other words, the degree to which the image’s pixels are modified in order to encode them with the message.

An increase in intensity, then, increases the durability, but it may also decrease image quality slightly by making the pixel changes more visible. When the changes become visible, they can appear as a slight texture or grain in the image. Similarly, a decrease in intensity results in better image quality, but the embedded message is less durable. Because of this interaction between durability and image quality, it is the second priority of Image Optimizer to preserve image quality as much as possible.

JPEG compression and MagiCompression makes the balancing act between message durability and image quality becomes a bit more challenging. Since JPEG is a lossy compression method, it has an obvious negative effect on image quality. It can also affect message durability, since any degradation of the image itself will also degrade the robustness of the embedded message. Of course, the impact of these variations is dependent on your chosen compression level and the actual content of the image. In turn, the level of compression you choose is usually influenced by how the image will be used. For example, images that will be posted on a Web site are usually compressed rather aggressively to speed up their display in the user’s browser; as a result, it may be quite acceptable to embed at a higher intensity with these images — the resulting durability helps to ensure the persistence of the embedded message, and the increased visibility will often not be noticeable with medium-resolution JPEG images.

Image Optimizer is designed to help you balance these factors, providing you with controls that affect this important interaction.

Use the Intensity slider to specify the starting intensity

Use the Minimum Durability edit box to specify the desired minimum durability

Image Optimizer will then work iteratively to achieve the desired durability by:

Increasing the intensity

Decreasing the MagiCompression

Increasing the Quality

Introduction to watermarking