Convolutional Neural Network-Based Image Watermarking
using Discrete Wavelet Transform
Alireza Tavakoli1†, Zahra Honjani2†, and Hedieh Sajedi2*
*Correspondence: hhsajedi@ut.ac.ir
1Department of Computer Engineering, School of Electrical and Computer Engineering, College of
Engineering, University of Tehran, Tehran
2Department of Computer Science, School of Mathematics, Statistics and Computer Science, College of
Science, University of Tehran, Tehran
†These authors contributed equally to this work.
Abstract
With the growing popularity of the Internet, digital images are used and transferred more
frequently. Although this phenomenon facilitates easy access to information, it also creates secu-
rity concerns and violates intellectual property rights by allowing illegal use, copying, and digital
content theft. Using watermarks in digital images is one of the most common ways to maintain
security. Watermarking is proving and declaring ownership of an image by adding a digital water-
mark to the original image. Watermarks can be either text or an image placed overtly or covertly
in an image and are expected to be challenging to remove. This paper proposes a combination
of convolutional neural networks (CNNs) and wavelet transforms to obtain a watermarking net-
work for embedding and extracting watermarks. The network is independent of the host image
resolution, can accept all kinds of watermarks, and has only 11 layers while keeping performance.
Performance is measured by two terms; the similarity between the extracted watermark and the
original one and the similarity between the host image and the watermarked one.
Keywords— watermarking, convolutional neural networks, wavelet transform, neural networks
1 Introduction
Protecting art ownership was always an issue since painters used to sign their works, which was not safe.
Due to widespread Internet use, artistic works are becoming digital, so the threat of privacy, copyright, and
illegal usage has increased. Authentication is not limited to artistic works but includes identity document (ID)
cards and source tracking. In order to solve these issues, digital watermarking is an effective method of hiding
information that can be used for authentication purposes.
The digital watermarking technique involves embedding information (watermark) into the content and
extracting it when needed. Various attacks could be applied to the watermarked content to damage or remove
the embedded watermark, which shows the importance of robust watermarking. Even though watermarking
can be applied to a wide range of content, including video [1], audio [2], or images, in this paper, we will focus
on images.
Until recently, digital watermarking was based on deterministic algorithms. Typical methods are based
on embedding the watermark in one of the discrete cosine transform (DCT) [3], discrete wavelet transform
(DWT) [4–6], discrete Fourier transform (DFT) [7], or quantization index modulation [8], or a combination of
these [9,10].
Due to the inflexibility of deterministic algorithms, small changes in watermarked images lead to inaccurate
extracted watermarks. The inflexibility leads to using neural networks as a robust technique for digital water-
marking [11,12]. Even though these methods solve the robustness problem, some non-deterministic networks
still perform poorly, and others have complex structures.
This paper investigates the combination of deterministic and neural network methods to improve accuracy
and performance. As the results suggest, we have improvements in some attacks. In addition, the proposed
network enhances the quality of watermarked images by using DWT as a preprocessing technique.
The rest of the paper is organized as follows: In Section 2, we discuss relevant previous studies. Then in
Section 3, we outline the basic concept, wavelet transform, used for the proposed algorithm. The proposed
network structure is explained in Section 4. Section 5discusses the training technique, the experimental results,
and the comparison with literature [12], and [13]. Moreover, this paper is concluded in Section 6.
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arXiv:2210.06179v2 [eess.IV] 29 Oct 2022