## 4 Experimental Results and Discussion
### Comparative Study
\begin{table}
\begin{tabular}{p{71.1 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt} p{56.9 pt}} \hline
**Parameters** & **[PERSON] and [PERSON][18]** & **[PERSON][31]** & **[PERSON] and [PERSON][32]** & **[PERSON] and [PERSON][27]** & **[PERSON] et al.[23]** & **Proposed** \\ \hline Scheme & Non-blind & Blind & Blind & Blind & Blind & Blind \\ Embedding domain & DWT + SVD & Hadmard & LWT + d-sequence & DCT & IWT + SVD & IWT + SVD \\ Cover image size & 512 by 512 & 512 by 512 & 512 by 512 & 512 by 512 & 512 by 512 & 512 by 512 & 512 by 512 \\ Watermark size & 64 by 64 & 64 by 64 & 16 by 16 & 64 by 64 & 256 by 256 & 64 by 64 \\ Security & Yes & Yes & Yes & No & Yes & Yes \\ Encryption approach & Arnold & No & Arnold & No & Chaotic map & Pseudo \\ Optimization algorithm & ABC & DDFA & No & ACO & No & GA, ABC, FA \\ Handling FPE & No & Yes & Yes & Yes & Yes & Yes \\ Embedding position & Principal & Coefficients & Sub bands & DC & Principal & Principal \\  & component & adjustments & & component & component & component \\ Embedding type & Static & Dynamic & Static & Dynamic & Static & Dynamic \\ Embedding rate & 0.015625 & 0.015625 & 0.00097 & 0.015625 & 0.25 & 0.015625 \\ \hline \end{tabular}
\end{table} 
Table 10: Watermarking parameters of proposed scheme and state-of-the-art schemes [18; 23; 27; 31; 32]. Figure 15: PSNR of the proposed scheme and the schemes in comparison [18; 23; 27; 31; 32] for Lena and Baboon test cover images. Robustness Comparison: Robustness performance of the proposed scheme is compared with schemes in [18; 23; 27; 31; 32] using NC, under zero attacks as shown in Figure 16. The NC values of the proposed scheme are ideal/higher than other schemes [18; 23; 27; 31; 32] in comparison for \"Lena\" and \"Baboon\" images as can be seen in Figure 16. Further robustness performance is compared under image processing attacks and shown in Figure 17. The proposed scheme is more robust for rotation, sharpening, Gaussian filter, and median filter attacks against other schemes [18; 23; 27; 31; 32] in comparison. [18; 23; 27; 31; 32]. For JPEG compression, the proposed scheme is more robust than schemes in [18; 23; 31; 32] and shows almost similar performance to the scheme in [27]. For a salt and pepper attack, the proposed scheme performs better than the schemes in [18; 27; 32] but lags behind in comparison to the scheme in [31]. The majority of the attacks in the proposed scheme are more robust and show almost equal performance to schemes in [23; 27]. From this, it can be claimed that the proposed scheme is more robust than the state-of-the-art [18; 23; 27; 31; 32] schemes. Embedding rate: The embedding rate of the proposed adaptive embedding scheme is analyzed in this section. The number of watermark bits embedded in the cover image is termed as the embedding rate of the watermarking scheme. The embedding rate of the proposed scheme is calculated using Equation (16) as shown below:  
\[Embedding\ rate=\frac{Total\ number\ of\ watermark\ bits}{Total\ number\ of\ cover\ image\ pixels}bpp \tag{16}\]  
While calculating the embedding rate, the size of cover and the watermark are considered. The proposed scheme embedding rate is calculated using Equation (16) shown below:  
\[Total\ number\ of\ cover\ image\ pixels=512\times 512=262144\ pixels\]  
Figure 16: NC for the proposed scheme and watermarking schemes proposed in [18; 23; 27; 31; 32] (under zero attacks) for Lena and Baboon cover images. Figure 17: INC for the proposed scheme and state-of-the-art schemes [18; 23; 27; 31; 32] under attacks for Lena cover Image. _Total number of watermark bits \(=64\times 64=4096\) bits_  
\[Embedding\ rate = \frac{4096}{262144}=0.015625\,bpp\]  
The proposed scheme has an embedding rate of 0.015625 bpp. The embedding rate of the proposed scheme is higher than the scheme proposed in [32] and equal to schemes proposed in [18; 27; 31]. The proposed scheme providing high imperceptibility, robustness and security than the scheme proposed in [23] but under-performance in terms of embedding rate.