# A Robust and Secure Watermarking Approach Based on Hermite Transform and SVD-DCT
## 2 Related Work
They applied different attacks, compared their technique with other techniques, and demonstrated that their technique had better robustness. They did not include the watermarks extracted. Therefore, to evaluate different techniques and compare them, some papers focused on describing different watermarking algorithms. For example, [PERSON] et al. [30] explained that, to achieve the security of digital data, it is necessary to improve the watermarking techniques and to provide better robustness. The authors clarified that several algorithms utilize SVD to enhance the quality aspect of the embedded image, aiming to increase its resilience against various signal-processing attacks. The authors presented different metrics that are possible to use to evaluate different techniques and different transformations that researchers use commonly. In [31], [PERSON] et al. presented a combined bling digital image watermarking method using the DCT and DWT as spatial-frequency decomposition and SVD analysis to ensure all requirements, according to the authors, that a watermarking algorithm must satisfy, for example imperceptibility, safety, resilience, and capacity of the payload. As a watermark, they used a digital image and encrypted it with the Arnold map. They presented results using only one image and only one watermark. [PERSON] et al. [32] proposed a new technique called the Porcellio Scaber Algorithm (PSA). They explained that, with this algorithm, the visual perception of the extracted watermark was good and, at the same time, maintained robustness. Their proposal was a bling watermarking and used a redundant version of the DWT (RDWT), DCT, and SVD. In addition, they embedded a LOGO into the host image. They reported a high PSNR value of 73.7205 dB in the watermarked image (_Lena_). Other hybrid algorithms were developed by [PERSON], [PERSON] et al. [33; 34]. On the one hand, in [33], they presented a scheme using SVD (to improve robustness), the DWT, and the DCT. Their proposal included a process to encrypt the watermark by an SVD ghost imaging system. As a watermark, they used a digital image with a size of \(32\times 32\). The authors did not indicate the parameters of the attacks that they employed to evaluate their method. On the other hand, in [34], a watermarking method using a decomposition by the DWT of four levels in conjunction with an SVD analysis was presented. They proposed four levels of the DWT to significantly enhance the imperceptibility and the robustness of the method. The evaluation of the algorithm showed good results using the PSNR, NCC, and SSIM. As a watermark, they used a digital image with a size of \(32\times 32\). [PERSON] et al. described in [35] a hybrid SVD-DWT. They explained that the Human Visual System (HVS) is less sensitive to high-frequency coefficients, so they chose them to insert the watermark and to avoid poor results when extracting the watermark, they aggregated SVD. As we can see, different watermarking algorithms for digital images have been developed for copyright protection, and the majority are focused on the principal problem, which is robustness. In this paper, a watermarking method including imperceptibility, robustness, watermark capacity, and computational cost for copyright protection is presented.