Digital Watermarking

There are two types of digital watermarking:

• Visible Digital Watermarking: Visible data is embedded as the watermark. This can be a logo or a text that denotes a digital medium's owner.
• Invisible Digital Watermarking: The data embedded is invisible or, in case of audio content, inaudible.

Robust watermarks involve blending signal amplitude with large bandwidth sizes and a short message length. Frequency domain capabilities and mixed-domain techniques, when added to signals, are believed to provide the right amount of robustness in order to guard against watermark attacks.

The publisher Playboy has used an invisible form of digital watermarking to detect where its copyrighted material has been illegally posted on other websites.