# An Innovative Recompression Scheme for VQ Index Tables
## 4 Experimental Results
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & \multicolumn{4}{c}{\(n=2\)} \\ \hline
**Images** & **SOC**[24] & **Improvement Rate** & **State Codebook**[26] & **Improvement Rate** & **Ours** \\ \hline Elaine & 0.5064 & 14.87\% & 0.5011 & 13.97\% & 0.4311 \\ Lena & 0.4501 & 11.89\% & 0.4441 & 10.71\% & 0.3965 \\ Pepper & 0.4585 & 13.27\% & 0.4499 & 12.14\% & 0.3953 \\ Wine & 0.4127 & 11.49\% & 0.4055 & 9.91\% & 0.3653 \\ Woodland & 0.5322 & 13.16\% & 0.5270 & 12.29\% & 0.4622 \\ Zelda & 0.4869 & 14.42\% & 0.4902 & 14.99\% & 0.4167 \\ \hline Average & 0.4740 & 13.26\% & 0.4696 & 12.44\% & 0.4112 \\ \hline \multicolumn{5}{c}{\(n=3\)} \\ \hline
**Images** & **SOC**[24] & **Improvement Rate** & **State Codebook**[26] & **Improvement Rate** & **Ours** \\ \hline Elaine & 0.4878 & 12.27\% & 0.4881 & 12.33\% & 0.4279 \\ Lena & 0.4378 & 8.04\% & 0.4378 & 8.03\% & 0.4026 \\ Pepper & 0.4462 & 9.70\% & 0.4457 & 9.60\% & 0.4029 \\ Wine & 0.4196 & 8.46\% & 0.4177 & 8.05\% & 0.3841 \\ Woodland & 0.5112 & 10.96\% & 0.5093 & 10.63\% & 0.4552 \\ Zelda & 0.4743 & 11.82\% & 0.4809 & 13.03\% & 0.4183 \\ \hline Average & 0.4628 & 10.30\% & 0.4633 & 10.38\% & 0.4152 \\ \hline \multicolumn{5}{c}{best \(n\)} \\ \hline
**Images** & **SOC**[24] & **Improvement Rate** & **State Codebook**[26] & **Improvement Rate** & **Ours** \\ \hline Elaine & 0.4878 & 12.27\% & 0.4881 & 12.33\% & 0.4279 \\ Lena & 0.4378 & 9.43\% & 0.4378 & 9.41\% & 0.3965 \\ Pepper & 0.4462 & 11.40\% & 0.4457 & 11.30\% & 0.3953 \\ Wine & 0.4127 & 11.49\% & 0.4055 & 9.91\% & 0.3653 \\ Woodland & 0.5112 & 10.96\% & 0.5093 & 10.63\% & 0.4552 \\ Zelda & 0.4743 & 12.15\% & 0.4809 & 13.36\% & 0.4167 \\ \hline Average & 0.4617 & 11.30\% & 0.4612 & 11.22\% & 0.4095 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Comparison of the bit rates of other schemes with the proposed scheme using a VQ codebook with 512 codewords. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & & \multicolumn{4}{c}{best \(n\)} \\ \hline
**Images** & **SOC**[24] & **Improvement Rate** & **State Codebook**[26] & **Improvement Rate** & **Ours** \\ \hline Elaine & 0.3940 & 13.12\% & 0.3858 & 11.28\% & 0.3423 \\ Lena & 0.3662 & 10.28\% & 0.3538 & 7.13\% & 0.3286 \\ Pepper & 0.3726 & 12.27\% & 0.3602 & 9.25\% & 0.3269 \\ Wine & 0.3545 & 10.44\% & 0.3393 & 6.43\% & 0.3175 \\ Woodland & 0.4113 & 11.18\% & 0.3988 & 8.40\% & 0.3653 \\ Zelda & 0.3939 & 14.41\% & 0.3887 & 13.26\% & 0.3371 \\ \hline Average & 0.3821 & 11.99\% & 0.3711 & 9.38\% & 0.3363 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: _Cont._  
Figure 14: Comparison of the bit rates of the proposed scheme using a VQ codebook with 1024 codewords for different values of \(r\) at \(n=2\) and \(n=3\). Figure 13: Comparison of the bit rates of the proposed scheme using a VQ codebook with 512 codewords for different values of \(r\) at \(n=2\) and \(n=3\). Figure 16: Comparison of the bit rates of other schemes and the proposed scheme (\(r=4\)) with the proposed scheme (\(r=5\)) using a VQ codebook with 1024 codewords at \(n=3\). Figure 15: Comparison of the bit rates of other schemes and the proposed scheme (\(r=4\)) with the proposed scheme (\(r=5\)) using a VQ codebook with 1024 codewords at \(n=2\). In order to compare JPEG 2000 (Lossless Mode) [28] and PNG [29] compression techniques, we set the codebook size to 256 and selected images from the BOWS-2 dataset [30] for VQ codebook training. Figure 17 shows the comparison of the average bit rate results on the BOWS-2 dataset, where SOC, state codebook, and our scheme set \(n=2\). In the comparison, our scheme also sets \(r=4\). We can see that our proposed scheme still achieves the best compression effect with a bit rate of 0.3234.