# Haze Removal Based on Refined Transmission Map for Aerial Image Matching
## 4 Conclusions  
A dehazing method for image contrast enhancement was proposed. The method modifies the transmission map based on the DCP using the HMRF-EM algorithm. The method can enhance the image contrast by reducing the block artifacts caused by a patch-based image dehazing algorithm. The performance of the proposed algorithm was found to be superior to that of conventional methods for synthetic, outdoor, and aerial images. The algorithm is suitable for image-matching based on local feature points and outperforms conventional methods. The algorithm has certain limitations. For example, it can only be applied to RGB-based images, excluding satellite images without a blue band. The performance of the algorithm is also degraded when haze affects near-infrared channels.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**S. No** & **Tested Image** & **[PERSON] et al. [35]** & **[PERSON] et al. [40]** & **[PERSON] et al. [41]** &
\begin{tabular}{c} **Proposed** \\ **Method** \\ \end{tabular} \\ \hline
1 & Figure 4 & 20.8522 & 23.7638 & 34.5783 & **15.5900** \\
2 & Figure 4 & 26.1828 & 27.0469 & 36.8676 & **21.5313** \\
3 & Figure 4 & 41.0633 & 50.6249 & 53.1791 & **33.1987** \\
4 & Figure 4 & 31.3141 & 27.8593 & 39.0135 & **25.7796** \\
5 & Figure 7 & 40.0932 & 61.6822 & 34.7334 & **29.7811** \\
6 & Figure 7 & 40.8646 & 65.8164 & 39.7221 & **35.5101** \\
7 & Figure 7 & **33.0525** & 70.4645 & 34.9615 & 34.7679 \\
8 & Figure 7 & 36.9200 & 47.7217 & 36.3100 & **26.1627** \\
9 & Figure 8 & **25.8414** & 72.7626 & 28.4863 & 28.7927 \\
10 & Figure 8 & 26.0668 & 60.1055 & 26.7333 & **22.1936** \\
11 & Figure 8 & **26.5691** & 76.9486 & 31.8643 & 30.3427 \\
12 & Figure 8 & 32.6156 & 60.5336 & 34.9176 & **32.0359** \\ \hline \hline \end{tabular}
\end{table}
Table 1: Quantitative comparison of different methods based on PIQE evaluation.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**S. No** & **Tested Image** & **[PERSON] et al. [35]** & **[PERSON] et al. [40]** & **[PERSON] et al. [41]** &
\begin{tabular}{c} **Proposed** \\ **Method** \\ \end{tabular} \\ \hline
1 & Figure 4 & 24 & **102** & 62 & 92 \\
2 & Figure 4 & 55 & 217 & 184 & **254** \\
3 & Figure 4 & 31 & 74 & 46 & **85** \\
4 & Figure 4 & 152 & 351 & 203 & **352** \\
5 & Figure 7 & 17 & 13 & 19 & **30** \\
6 & Figure 7 & 18 & 56 & 25 & **71** \\
7 & Figure 7 & 08 & 35 & 15 & **55** \\
8 & Figure 7 & 29 & 67 & 72 & **108** \\
9 & Figure 8 & 52 & **47** & 66 & **123** \\
10 & Figure 8 & 114 & 132 & 171 & **405** \\
11 & Figure 8 & 10 & 17 & 42 & **74** \\
12 & Figure 8 & 58 & 56 & 82 & **177** \\ \hline \hline \end{tabular}
\end{table}
Table 2: Quantitative comparison of feature-points matching obtained from different methods.  
The performance of the delta functions, one of the basic assumptions of the proposed algorithm, can also be adversely affected when realistic camera sensitivities are used.  
Conceptualization, Y.R.M. and O.-S.K.; methodology, Y.R.M. and O.-S.K.; investigation, Y.R.M. and O.-S.K.; writing--original draft preparation, Y.R.M. and O.-S.K.; writing--review and editing, Y.R.M. and O.-S.K.; supervision, O.-S.K.; project administration, O.-S.K. All authors have read and agreed to the published version of the manuscript.  
This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT & Future Planning (2019 RI1F11058489).  
Not applicable.  
The publicly archived NH-HAZE dataset is available at [[https://data.vision.ee.ethz.ch/cvl/ntire20/nh-haze](https://data.vision.ee.ethz.ch/cvl/ntire20/nh-haze)]([https://data.vision.ee.ethz.ch/cvl/ntire20/nh-haze](https://data.vision.ee.ethz.ch/cvl/ntire20/nh-haze)) (accessed on 26 July 2021) and manually annotated dataset is generated during the study which is available at [[https://unsplash.com/s/photos/aerial](https://unsplash.com/s/photos/aerial)]([https://unsplash.com/s/photos/aerial](https://unsplash.com/s/photos/aerial)) (accessed on 26 July 2021).  
The authors declare no conflict of interest.