Imatag, a product of startup LAMARK, protects images with digital watermarking. What is this?
Our white paper gives a description. Here are some new facts.
The great confusion: Visible and invisible watermarking
The term “Digital watermarking” was coined by the research labs, which invented this new technology.
Yet, in digital photography, this wording brings a lot of confusion since photographers have been using “watermarking” for a long time. These two “watermarking” are not the same.
- Digital watermarking provided by Imatag adds an invisible watermark to the picture. The pixel values are changed in order to convey a secret message, but these modifications are subtle and perceptually shaped. The human eye cannot see the difference between the watermarked and the original image. This is a major difference with visible watermark which is an overlay superposed on top of the picture and meant to be seen.
- Digital watermarking embeds a secret message within the image. This message is binary and can be decoded by a computer.
This is the second major difference with visible watermarks which are meant for human readers.
To avoid the confusion, we should speak about invisible digital watermarking.
In some languages (in French for instance), this technology is also called “digital tattoo”. This conveys the idea of robustness. Even if the image has been edited (JPEG compression, cropping, scaling, color editing …), the computer can find back the embedded message. This message sticks to the image as a tattoo on the skin.
Invisible digital watermarking is not new
The first research works date back to 25 years ago. This technology is now well spread because it can be applied to many types of content (still images, video, audio, source code, maps, 3D model, ADN sequence, chemical compound, …) and its use cases are legions. You probably have already seen or heard watermarked content without knowing it. This is just the point: digital watermarking is invisible, or inaudible, imperceptible…
Invisible digital watermarking is everywhere
Some applications of this technology are the following:
In Europe and in the USA, the audio of TV channels is watermarked. The embedded message encodes the name of the channel.
Panelists have at home a device capturing the sound in their TV room. It decodes the message and sends it to the monitoring companies via Internet. They can measure the audience and market share live.
In Africa, the TV ads are typically long spots. They are broadcasted through many local channels which sometimes shorten the ads to increase their number and whence the revenues. The embedded message is the identifier of the TV spot followed by a time-code. Some companies have platform listening to all TV channels 24hours a day and check that any single second of a TV spot is duly broadcasted.
The audio of movies are watermarked in theaters and on Blu-Ray discs. The decoder is embedded in a Blu Ray disc player.
If it detects a watermark while playing a content in the clear, it concludes that this content is indeed a pirated copy (either a camcord of a theater projection or a ripped Blu Ray) and it stops the playback.
Videos in movie theaters are also watermarked. The embedded message is the date of the projection and also the ID of the beamer. That way, “Hollywood” knows in which theater a pirate has camcorded a movie and puts the pressure on the owner of the theater.
Websites selling multimedia content on demand (movies, songs, cartoons, e-books) send the client a personalised copy of the content. The ID of the client is embedded so that dishonest people illegally sharing their versions (like on P2P networks) are identified and black-listed (or sued).
Some companies use digital watermarking as a replacement of the bar code on packaging.
In short: digital watermarking is invisible, not new and already used in many applications.
Also published on Medium.