Client-side embedding watermarking protocols can achieve a high level of efficiency in applying the watermark protection, since they adopt an enciphering scheme that only requires computations of modular additions, whereas the other schemes based on homomorphic encryption often require computations of modular exponentiations, which are much more expensive than modular additions.
The latter depends on the watermarking insertion scheme and occurs when a coalition of buyers combine their differently watermarked copies in order to obtain a new copy in which the watermark is much harder to be detected.
There are for types for digital watermark techniques 1) visible; 2) invisible-robust; 3) invisible-fragile; 4) dual.
This paper propose the use of biometric identity as watermark in order to link digital image to the person who capture it .
1) The proposed modified watermarking approach embeds watermark data into a high-entropy region by using DT-CWT.
Section 2 presents the proposed watermarking method that consists of watermark embedding and decoding.
It is necessary to check the host image in order to determine whether the selected points (regions of interests) are suitable places to embed watermark
Watermarking embedding and watermark
and original image extraction schemes are given in Figures 3 and 4, respectively.
Authors in  proposed a watermarking algorithm based on visual cryptography for multiple watermarks
Watermarking is simply a process of concealing some sort of data (watermark
) into either of the same kind or of different type data (host) .
The research admits that the usage of thin lines and shadows makes removal of a watermark
difficult albeit given a single image.
In , CS is employed to process watermark
, which strengthens the security of watermark