# Imperceptible-Visible Watermarking to Information Security Tasks in Color Imaging
###### Abstract  
Digital image watermarking algorithms have been designed for intellectual property, copyright protection, medical data management, and other related fields; furthermore, in real-world applications such as official documents, banknotes, etc., they are used to deliver additional information about the documents' authenticity. In this context, the imperceptible-visible watermarking (IVW) algorithm has been designed as a digital reproduction of the real-world watermarks. This paper presents a new improved IVW algorithm for copyright protection that can deliver additional information to the image content. The proposed algorithm is divided into two stages: in the embedding stage, a human visual system-based strategy is used to embed an owner logotype or a 2D quick response (QR) code as a watermark into a color image, maintaining a high watermark imperceptibility and low image-quality degradation. In the exhibition, a new histogram binarization function approach is introduced to exhibit any watermark with enough quality to be recognized or decoded by any application, which is focused on reading QR codes. The experimental results show that the proposed algorithm can embed one or more watermark patterns, maintaining the high imperceptibility and visual quality of the embedded and the exhibited watermark. The performance evaluation shows that the method overcomes several drawbacks reported in previous algorithms, including geometric and image processing attacks such as JPEG and JPEG2000. n pacs: 27 July 2021 +
Footnote †: 24 September 2021  
==WARNING: Truncated because of repetitions==
mean value \(m\) is satisfied by Equation (1). \[m=\left\{ \begin{array}{ll}\min(\overline{R}_{R},\overline{R}_{G},\overline{R }_{B}),&\mbox{if}\;\;\min(\overline{R}_{R},\overline{R}_{G},\overline{R}_{B} )\geq T,\\ \max(\overline{R}_{R},\overline{R}_{G},\overline{R}_{B}),&\mbox{otherwise}, \end{array} \right.\] (1)  
where \(\overline{R}_{k}\) and \(T\) = 2 correspond to the mean value of the embedding region in the color channel \(k\) and an empirical strength of the embedding strategy, respectively. To embed a binary watermark pattern \(W\) = \(\{w_{i}\,|\,w_{i}\,=\,0,I,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\, \,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\
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image is obtained, it is distributed to the end-users by on-demand or streaming services, and the exhibition stage leverages the processing capabilities of the display devices to exhibit the watermark to the HVS by the mechanism called binarization function. In this algorithm, \(n\) binary watermarks \(W\) = {\(w_{i}\) | \(w_{i}\) = 0,1, and \(i\) = 1, 2, 3,..., \(M\times N\)} are embedded into \(n\) non-overlapping embedding regions \(R_{n}\)\(\in\)\(I_{k}\) selected with the smallest variance from the color image \(I_{k}\), \(k\)\(\in\)\(\{R\), \(G\), \(B\}\), as shown in Equation (5). \[R_{w}(p_{i})=\left\{ \begin{array}{ll}\max(0,\mu_{R_{n}}-\Delta JND(p_{i})),&if \;\;w_{i}=0,\\ \min\;\;(\mu_{R_{n}}+\Delta JND(p_{i}),255),&if\;\;w_{i}=1,\end{array} \right. \tag{5}\]  
where \(\mu_{Rn}\) and \(R_{w}(p_{i})\) are the mean value of the \(n\)-\(th\) region and the \(i\)-\(th\) pixel value of the watermarked region, respectively; \(\Delta JND(p_{i})\) is the JND-based embedding strength [29], where \(\Delta\) = 0.5 corresponds to the imperceptibility factor.