# A Survey on Robust Video Watermarking Algorithms for Copyright Protection
## 4 Robust Watermarking Algorithms Based on Original Videos
### Video Watermarking in Transform Domain
#### 4.2.2 DWT-Based Watermarking Algorithms  
Due to the excellent spatial localization, frequency spread, and multiresolution characteristics of the methods in the wavelet domain, many algorithms based on DWT are gaining popularity. [PERSON] et al. [44] proposed an adaptive video watermarking algorithm based on visual models. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Ref.** & **Type** & **Watermark Preprocessing** & **Embedding Position** \\ \hline
[34] & Blind & Arnold transform & High-frequency coefficients of R, G, and B components \\
[35] & Blind & CDMA & DCT coefficients of Y component \\
[36] & Blind & - & Robust DCT coefficients selected in Y component \\
[37] & Non-blind & - & Selected coefficients in KDCT matrix of Y component \\
[38] & Semi-blind & Arnold transform & Low-frequency DCT coefficients of Y component \\
[40] & Blind & Permuted processing & AC values of selected DCT blocks in Y component \\
[41] & Blind & Pseudorandom generator & Y component of each I frame \\
[43] & Blind & - & AC coefficients of each 2D DCT block in Y component \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Summary comparison of several watermarking algorithms in DCT domain. To obtain JND masking, the visual model is designed by analyzing luminance masking, texture masking, and entropy masking. On the basis of the JND threshold, the scrambled watermark is embedded in mid-frequency coefficients. [PERSON] et al. [45] embedded different parts of the watermark into several shots of a video sequence. On the basis of the motion activity analysis, region complexity and motion information are combined to separate different regions of the original video into perceptually distinct categories. The embedding positions of the watermark are adjusted adaptively based on HVS. In another previous paper [46], shot detection was adopted to obtain key frames and moving frames from the video, and watermark bits were embedded into two high-frequency coefficients of the first-level DWT randomly. Based on matching at least two feature points generated by scale invariant feature transform (SIFT) in the original video frame and the frame containing watermarks, the frame that is subject to rotation attacks can be recovered. On the basis of integer wavelet and SIFT, [PERSON] et al. [47] proposed a video dual watermarking algorithm to resist geometric attacks. The integer wavelet transform is adopted to divide the video frame into a low-frequency sub-band and a medium-high frequency sub-band. For coefficients in the medium-high frequency sub-band, various motion characteristics are calculated using the block matching algorithm, and then the threshold of human visual masking based on the video frame can be obtained. As a result, the watermark is inserted into the medium-high frequency sub-band adaptively. For coefficients in the low-frequency sub-band, due to the stability of the coefficient histogram to geometric attacks, the watermark is embedded into the neighboring bins. In a past paper [48], to achieve a compromise between the invisibility of the watermark and adaptability to attacks, the watermark was embedded into the second level of the medium-high frequency wavelet coefficients using the secret key and quantization method. In addition, the use of error correction codes and the scheme that embeds the same watermark in different frames redundantly play a great role in improving the performance of the algorithm. On the basis of [48], [PERSON] and [PERSON] [49] proposed a robust watermarking algorithm based on quantization and spread spectrum technology. An optimal quantization model based on the characteristics of HVS is introduced to quantize wavelet coefficients selected from different sub-bands, and then the watermark embedding process can be achieved. To prevent the collusion attack, [PERSON] et al. [50] adopted DWT to resize frames into 512 \(\times\) 512 based on security model, and the maximum mean values of LL and HL bands were used to select watermark positions.