# Generative Image Steganography via Encoding Pose Keypoints
## 4 Evaluation and Comparisons
### Robustness  
Robustness is an important indicator for evaluating the performance of steganographic methods, mainly measuring their ability to withstand attacks and, specifically, their performance in terms of information extraction accuracy when subjected to interference. During transmission, stego-images may be affected by noise, filtering, and other image attacks. Figure 9 shows the state of the stego-images generated by the proposed method after  
\begin{table}
\begin{tabular}{l c c} \hline \hline
**Method** & **Size** & **Capacity (Bits/Carrier)** \\ \hline [PERSON] [11] & Not limit & 1\(\sim\)15 \\ [PERSON] [12] & \(128\times 128\times 3\) & 15 \\ [PERSON] [18] & \(128\times 128\times 3\) & 33 \\ [PERSON] [23] & \(256\times 256\times 3\) & 64 \\ [PERSON] [34] & \(256\times 256\times 3\) & 128 \\ [PERSON] [15] & \(256\times 256\times 3\) & 256\(\sim\)1536 \\ Proposed Method & \(176\times 256\times 3\) & 713.6 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Capacity of the different steganography.  
\begin{table}
\begin{tabular}{l c c c} \hline \hline \multirow{2}{*}{**Method**} & \multicolumn{3}{c}{**Payload**} \\ \cline{2-4}  & **0.5 \(\times\) 256** & **1 \(\times\) 256** & **2 \(\times\) 256** \\ \hline [PERSON] [17] & 122.96 & - & - \\ [PERSON] [14] & 103.29 & 103.73 & 104.31 \\ IDEAS [15] & 98.57 & 98.63 & 101.45 \\ [PERSON] [18] & 36.46 & - & - \\ [PERSON] [22] & 14.89 & 15.63 & 15.76 \\ Proposed Method & 19.21 & 34.41 & 97.20 \\ \hline \hline \end{tabular}
\end{table}
Table 3: FID of the different steganography.  
encountering common image attacks. The robustness of the stego-image in covert communication was evaluated through simulation experiments, and the bit error rate (\(BER\)) defined by Formula (6) was used to quantify its impact.  
\[BER=\frac{\sum_{i=1}^{m}p_{i}\oplus q_{i}}{m}\times 100\% \tag{6}\]  
In this equation, \(m\) is the length of the secret bitstream; \(p\) is the original secret bitstream; and \(q\) is the extracted secret bitstream. When the \(BER\) is zero, it indicates that no errors occurred during the extraction of the secret bitstream. This result indicates that the proposed method is fully robust against such attacks; on the other hand, if the \(BER\) is greater than zero, it means that a certain number of error bits occurred during the extraction process, suggesting that some bits have been modified during the attack process. Therefore, the robustness of this method against such attacks is not entirely reliable.  
This section carried out multiple sub-experiments on the above-mentioned different image attack methods. Firstly, the average information extraction bit error rate of the proposed method under different pose estimation networks [30; 35; 30] was compared. The results are shown in Figure 10. Among them, the parameters of Gaussian noise, salt and pepper noise, median filtering, mean filtering, Gaussian filtering, and JPEG compression are 0.001, 0.001, 3 \(\times\) 3, 3 \(\times\) 3, 3 \(\times\) 3, and Quality-90, respectively. Subsequently, the average information extraction bit error rates of each method were compared, and the results are presented in Table 4. The experimental results demonstrate that since the proposed method relies on the pose estimation network optimized for steganography applications in the effect of extracting secret information, its robustness effect is more significant compared to some common steganography methods.  
Figure 10: Robustness comparison under different attitude estimation networks.  
Figure 9: Examples of different image attacks.