Currently, watermarking techniques based on transform domain are more popular than those based on time domain since they provide higher audio quality and much more robust watermark.
In this attack, a coalition of customers combine their differently watermarked copies in order to obtain a new copy in which the watermark is much harder to be detected.
Check 'Include watermark' in the 'Watermark' section.
Namely, the first solution has a constant performance gain for low watermark-to-noise ratios and appears much more convenient for high watermark-to-noise ratios.
In [13], we proposed a new contourlet-based image watermarking method which embeds a grayscale watermark with as much as 25% of the host image size in the 16th directional subband of the host image.
However, using grayscale images as watermarks has drawn much attention for copyright protection since many logos are grayscale in nature.
Digital watermarking technology received much attention for resolving such a concern because this technology could hide information into the multimedia object (e.g., images, audio, and video) for applications like intellectual property protection, content authentication, and fingerprinting.
However, for an invisible watermarking scheme, the quantified perceptual difference between an original image and its watermarked version would naturally be much lower than that for a visible watermarking scheme.
A watermark should convey as much information as possible, statistically detectable, enough to identify ownership and copyright unambiguously.
Hence, in the lower frequencies of an audio-like colored host, the per-channel watermark signal will be much larger than the corresponding to higher-frequencies.
