# Fast Segmentation Algorithm for Cytoid Macular Edema Based on Omnidirectional Wave Operator
## 3 Results
When designing the algorithm, based on experience, we believe that an arbitrarily shaped target with a closed contour needs to be segmented in eight directions, but in actual experiments, we found that segmentation in four directions is sufficient to determine any closed curve contour. In order to better explain this, we considered four directions, six directions, and eight directions, and calculated the evaluation index of the segmentation results in the corresponding number of directions. Figure 7 shows the segmentation results of the three cases. Table 2 shows four evaluation indicators. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & \multicolumn{3}{c}{**DRLSE**} \\ \hline  & **Expert A** & **Expert B** & **Expert C** & **Average** \\ \hline Dice & 0.516 & 0.558 & 0.611 & 0.562 \\ \hline Precision & 0.969 & 0.982 & 0.971 & 0.974 \\ \hline Recall & 0.352 & 0.390 & 0.445 & 0.396 \\ \hline F1-Score & 0.516 & 0.558 & 0.610 & 0.563 \\ \hline  & \multicolumn{3}{c}{**Snake**} \\ \hline  & **Expert A** & **Expert B** & **Expert C** & **Average** \\ \hline Dice & 0.742 & 0.709 & 0.799 & 0.750 \\ \hline Precision & 0.968 & 0.877 & 0.909 & 0.918 \\ \hline Recall & 0.601 & 0.596 & 0.713 & 0.637 \\ \hline F1-Score & 0.742 & 0.710 & 0.799 & 0.752 \\ \hline  & \multicolumn{3}{c}{**Proposed Algorithm**} \\ \hline  & **Expert A** & **Expert B** & **Expert C** & **Average** \\ \hline Dice & 0.772 & 0.782 & 0.880 & 0.811 \\ \hline Precision & 0.898 & 0.864 & 0.902 & 0.888 \\ \hline Recall & 0.678 & 0.714 & 0.859 & 0.750 \\ \hline F1-Score & 0.773 & 0.782 & 0.880 & 0.813 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Comparison of evaluation indexes of segmentation results. It can be seen from Figure 7 that the four-direction operator and eight-direction operator have better segmentation performance than the six-direction operator, and the six-direction operator cannot fully identify the cyst. From the results of the evaluation indicators, the difference between the Dice index and the F1-score is very small, and they have similar segmentation performance. We choose the four-direction operator instead of the eight-direction operator, considering the following aspects:  
(a) Recall rate is more important in disease detection applications. In disease screening and testing, we pay more attention to the anti-missing rate. Even if the anti-error detection rate (accuracy) is low, error detection can be avoided by secondary screening or in-depth inspection. We cannot tolerate missed inspections more than false inspections. Operators in four directions have a higher anti-missing rate than operators in eight directions. (b) The authenticity of medical images. In the calculation process of six and eight directions, the rotated operator will change the image pixel distribution to a certain extent and affect the segmentation result. The four-direction operator does not. Even though such an impact is small, in the medical image process, the authenticity of the medical image should be maintained. (c) Calculating speed. We compared the processing speed of the operator with different numbers of operating directions. In the CME detection experiment, the four-direction operator takes 1.2 s, the six-direction operator takes 1.273 s, and the eight-direction operator takes 1.286 s. The smaller the number of directions, the shorter the calculation time of the algorithm.