# X-ray Image Enhancement Based on Adaptive Gradient Domain Guided Image Filtering
## 4 Experimental Results
Figure 4a shows the original X-ray image 4; Figure 4b is the result computed by McCann--the image is too bright; Figure 4c depicts the image enhanced by RLBHE--the image is too dark; Figure 4d is the result achieved by RESIHE--the effect of enhancement is not obvious; the image obtained by TBCSSR is shown in Figure 4e--the image is dark; Figure 4f is the result enhanced by GDGF--the details of the image are well preserved; Figures 4g and 4h are the results enhanced by SMIPC and FuzzyII, respectively; Figure 4i is the result calculated by our approach. Table 4 shows evaluation data in Figure 4, and we can notice that the values of AG, H, ALC, SF and MG are the best. We used eight image enhancement methods to experiment on 69 X-ray images, which we collected from the website [[http://acm.cs.nctu.edu.tw/](http://acm.cs.nctu.edu.tw/)]([http://acm.cs.nctu.edu.tw/](http://acm.cs.nctu.edu.tw/)) (accessed on 20 September 2022), and the corresponding average data are shown in Table 5. From this table, we can notice that the values of AG, H, ALC SF and MG are the best. Through the above comprehensive analysis, the experiment results show that our method has obvious advantages in terms of both subjective and objective evaluations. \begin{table}
\begin{tabular}{c c c c c c} \hline  & **AG** & **H** & **ALC** & **SF** & **MG** \\ \hline McCann & 4.9747 & 7.3960 & 0.2901 & 9.1737 & 4.0981 \\ \hline RLBHE & 2.4721 & 6.6451 & 0.0514 & 4.2870 & 2.0405 \\ \hline RESIHE & 5.4976 & 7.6038 & 0.4383 & 9.8437 & 4.5322 \\ \hline TBCSSR & 6.1722 & 6.6784 & 0.6021 & 11.0394 & 5.1153 \\ \hline GDGF & 7.0291 & 7.6321 & 0.6090 & 11.4703 & 5.7992 \\ \hline SMIPC & 4.9663 & 7.6440 & 0.3823 & 9.1813 & 4.0798 \\ \hline FuzzyII & 5.5589 & 7.4430 & 0.4732 & 10.0969 & 4.6027 \\ \hline Proposed & 7.8310 & 7.7382 & 0.8196 & 13.7265 & 6.5771 \\ \hline \end{tabular}
\end{table} 
Table 4: The metric data of eight methods on X-ray image 4. \begin{table}
\begin{tabular}{c c c c c c} \hline  & **AG** & **H** & **ALC** & **SF** & **MG** \\ \hline McCann & 4.0123 & 7.5435 & 0.2870 & 8.9464 & 3.4352 \\ \hline RLBHE & 2.2445 & 6.7002 & 0.0932 & 4.8208 & 1.8789 \\ \hline RESIHE & 4.5401 & 7.3486 & 0.4647 & 9.6568 & 3.8846 \\ \hline TBCSSR & 3.9534 & 5.8991 & 0.5479 & 9.4282 & 3.3742 \\ \hline GDGF & 5.1827 & 7.5822 & 0.8479 & 11.0629 & 4.4008 \\ \hline SMIPC & 4.0469 & 7.4819 & 0.4668 & 9.1315 & 3.4699 \\ \hline FuzzyII & 4.0409 & 7.3498 & 0.5045 & 9.2729 & 3.4821 \\ \hline Proposed & 6.6297 & 7.5951 & 0.8829 & 12.9503 & 5.6974 \\ \hline \end{tabular}
\end{table} 
Table 3: The metric data of eight methods on X-ray image 3. \begin{table}
\begin{tabular}{c c c c c c} \hline  & **AG** & **H** & **ALC** & **SF** & **MG** \\ \hline McCann & 4.5097 & 7.1685 & 0.2709 & 8.4758 & 3.7301 \\ \hline RLBHE & 2.9646 & 6.4171 & 0.1004 & 5.3958 & 2.4631 \\ \hline RESIHE & 5.3505 & 7.1441 & 0.4545 & 9.7358 & 4.4233 \\ \hline TBCSSR & 5.8109 & 6.2229 & 0.5695 & 10.6472 & 4.8123 \\ \hline GDGF & 6.3404 & 7.2809 & 0.5814 & 10.5298 & 5.2334 \\ \hline \end{tabular}
\end{table} 
Table 5: The average metric data of eight methods on 69 X-ray images.