*2.2. Data Enhancement*

In order to improve the robustness of the trained model, we used different processing methods to make data enhance for the famous and excellent tea image. In the research, we adopted the following methods:


In the dataset, 200 images were randomly selected each time for brightness enhancement, brightness reduction, contrast enhancement, contrast reduction, horizontal flip and random angle flip. After processing, the number of datasets reached 2049. Figure 4 reflects the results of data enhancement.

**Figure 4.** Data enhancement. (**a**) Original image, (**b**) brightness enhanced by 30%, (**c**) reduce brightness by 30%, (**d**) contrast enhancement 20%, (**e**) contrast reduction by 20%, (**f**) rotate counterclockwise by 30 degrees.
