# Assessment and Feasibility Study of Lemon Ripening Using X-ray Image of Information Visualization
## 3 Results  
Through DR, the X-ray radiographic DICOM grayscale images of the 3 lemons were obtained. After applying the quantitative comparison methods, fresh, mature, and overripe lemons were identified, as shown in Figure 2. Different X-ray intensities and different densities of the absorbers led to different signals. The low-density substances exhibited low absorption of ionizing radiation, meaning the ionizing radiation direction attenuation coefficients of the substances were also low. Thus, the exposure effect of the FPD to ionizing radiation was high, leading to low-signal (dark) images. On the other hand, the high-density substances exhibited high absorption of ionizing radiation, leading to high-signal (bright) images. Figure 2 shows the median-plane images (A) and the axial-plane images (B) of the lemons. (1), (2), and (3) represent different ripening of the lemons. These images are DICOM grayscale images of the (1) fresh, (2) mature, and (3) overripe lemons. According to the results, the images of the overripe lemon were low-signal (dark) images, while those of the fresh and mature lemons were high-signal (bright) images. The visual differences could be identified. However, it remains difficult to distinguish the fresh lemon from the mature one based on visual differences. Figure 1: The process of data visualization and statistical analyses. (**A**) Real lemons; (**B**) X-ray radiographic grayscale images with Digital Imaging and Communications in Medicine (DICOM) format; (**C**) a chromatographic image showing different tissue structures of the lemons; (**D**) a zoomed-in image showing the three solid layers of tissue structures of the lemons, namely peel, fiber, and pulp; (**E**) visualized images of the stratification analysis of the grayscale data. The acquired median-plane and axial-plane images were divided into three regions using multi-thresholding image segmentation for visualization of stratification. Figure 3 shows the median-plane and axial-plane results, displayed according to the three layers of the structure, namely the peel layer, the fiber layer, and the pulp layer (endocarp). Then the Kruskal-Wallis test was performed with the visualized grayscale value data for quantitative statistical analyses. The median-plane DICOM grayscale image of the lemons were transformed into visualized grayscale pixel matrix images, as shown in Figure 3. The visualized results of further stratification analyses of the grayscale pixel matrixes based on the three layers, namely the peel layer, the fiber layer, and the pulp layer, are shown in Figure 3B-D. The grayscale value of each pixel of each layer was marked on the matrix coordinate to create visual images showing all data on the same layer, as shown in Figure 3A. It can be seen that the grayscale pixel matrix stratification results presented in Figure 3A-C (1), and (2) were not different visually, while Figure 3D (1), (2), and (3) exhibited visual differences. The axial-plane DICOM grayscale images of the lemons were transformed into visualized grayscale pixel matrix images. Figure 4 shows the visualized results of further stratification analyses of the grayscale pixel matrixes. These results are corresponding to Figure 2B (1), (2), and (3). It can be seen that the grayscale pixel matrix stratification results presented in Figure 4B (1), (2), and (3) and Figure 4C (1) and (2) were not different visually, while Figure 4D (1), (2), and (3) exhibited visual differences. The grayscale value analyses and the visualized stratification analyses could only produce qualitative results based on partial visual differences. It was not possible to identify the freshness and ripening of the lemons. Thus, the grayscale matrixes were quantified and analyzed using quantified statistical analysis methods to perform scientific comparisons of the freshness and ripening of the lemons. The results are shown in Figure 5.  
Figure 2: X-ray radiographic images of (1) fresh, (2) mature, and (3) overripe lemons acquired at (**A**) median-plane and (**B**) axial-plane of the lemons.