Hasan Nayeem, Islam Md Saiful, Chen Wenyu, Kabir Muhammad Ashad, Al-Ahmadi Saad
School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu 611731, China.
Department of Software Engineering, Daffodil International University, Dhaka 1207, Bangladesh.
Sensors (Basel). 2021 Aug 17;21(16):5540. doi: 10.3390/s21165540.
This paper proposes an encryption-based image watermarking scheme using a combination of second-level discrete wavelet transform (2DWT) and discrete cosine transform (DCT) with an auto extraction feature. The 2DWT has been selected based on the analysis of the trade-off between imperceptibility of the watermark and embedding capacity at various levels of decomposition. DCT operation is applied to the selected area to gather the image coefficients into a single vector using a zig-zig operation. We have utilized the same random bit sequence as the watermark and seed for the embedding zone coefficient. The quality of the reconstructed image was measured according to bit correction rate, peak signal-to-noise ratio (), and similarity index. Experimental results demonstrated that the proposed scheme is highly robust under different types of image-processing attacks. Several image attacks, e.g., JPEG compression, filtering, noise addition, cropping, sharpening, and bit-plane removal, were examined on watermarked images, and the results of our proposed method outstripped existing methods, especially in terms of the bit correction ratio (100%), which is a measure of bit restoration. The results were also highly satisfactory in terms of the quality of the reconstructed image, which demonstrated high imperceptibility in terms of peak signal-to-noise ratio ( ≥ 40 dB) and structural similarity ( ≥ 0.9) under different image attacks.
本文提出了一种基于加密的图像水印方案，该方案结合了二级离散小波变换（2DWT）和离散余弦变换（DCT），并具有自动提取功能。基于对水印不可感知性与不同分解级别下嵌入容量之间权衡的分析，选择了2DWT。对选定区域应用DCT操作，使用之字形操作将图像系数聚合成单个向量。我们将相同的随机比特序列用作水印和嵌入区域系数的种子。根据比特校正率、峰值信噪比（）和相似性指数来衡量重建图像的质量。实验结果表明，所提出的方案在不同类型的图像处理攻击下具有高度鲁棒性。对水印图像进行了几种图像攻击，例如JPEG压缩、滤波、添加噪声、裁剪、锐化和位平面去除，我们提出的方法的结果超过了现有方法，特别是在比特校正率（100%）方面，比特校正率是比特恢复的一种度量。就重建图像的质量而言，结果也非常令人满意，在不同图像攻击下，峰值信噪比（≥40dB）和结构相似性（≥0.9）表明其具有高度不可感知性。
