# Improvements of Computational Ghost Imaging by Using Sequenced Speckle
## 3 Experiments and Simulation Results
The group comprising DD-1 and DD-3 falls within the speckle size range of 27 \(\upmu\)m to 540 \(\upmu\)m, while the group comprising DD-2 and DD-4 falls within the speckle size range of 27 \(\upmu\)m to 192 \(\upmu\)m. As shown in Figure 7b, the experimental results indicate that the CNR and resolution for the DD-1 and DD-3 groups are comparable to those of the DD-2 and DD-4 groups. The visibility of the retrieved ghost images and the horizontal line-outs of the normalized data also exhibit similar characteristics when visually inspected in Figure 7a. The numerical results related to the  
Figure 5: Retrieved CNR and resolution vs. speckle patterns obtained for TGI experiments. **(a)** Shows the retrieved ghost images and corresponding resolution. **(b)** Shows the retrieved CNR of the window-shaped object increased with higher speckle size, and the resolution was worse with higher speckle size. experiment and simulation data are presented in Figure 7b, along with the corresponding retrieved ghost images. To verify the universality of the proposed method, we also compare the CNR and resolution of the SGI with different speckle composition groups, as per the third rule. The third rule of the SGI consists of eight groups, and we conducted experiments and simulations to compare the CNR and resolution with the TGI, as shown in Figure 8. To ensure a fair comparison of the ghost image quality between the SGI and TGI under the same conditions, we evaluated the CNR of the retrieved ghost images, aiming for a  
Figure 6: Retrieved CNR and resolution of the SGI with different steps (DS) in both experiments and simulations. (**a**) illustrates the retrieved image and resolution of the window-shaped object for the experiment and simulation, respectively. (**b**) displays the retrieved CNR and resolution of the window-shaped object with different steps in both the experiment and simulation, respectively. The blue dashed lines represent the horizontal line-outs of the normalized data of the retrieved ghost images, while the solid blue curves represent the object. Figure 7: Retrieved CNR and resolution of the SGI with different speckle sorting directions (DD) in both experiment and simulation. (**a**) presents the retrieved image and resolution of the window-shaped object for the experiment and simulation, respectively. (**b**) demonstrates the retrieved CNR and resolution of the window-shaped object with different speckle sorting directions in both experiment and simulation, respectively. The blue dashed lines depict the horizontal line-outs of the normalized data from the retrieved ghost images, while the solid blue curves represent the object. resolution close to that of the TGI for the best CNR. The TGI achieved a highest CNR of 1.8873 with a speckle size of 164.5 \(\upmu\)m, corresponding to a resolution of approximately 1.10. Therefore, we mainly present the data with a resolution above 1.0 and their corresponding CNR in Figure 3:0  
Figure 8 showcases the experiments and simulations conducted for the DG-1 to DG-8 groups, respectively. For the DG-1, DG-5, and DG-7 groups, the mean speckle size step is 13.24 \(\upmu\)m within the speckle size range from 16.5 \(\upmu\)m to 496 \(\upmu\)m. Each small group in DG-1, DG-5, and DG-7 consists of 4, 6, and 8 speckle patterns, respectively. In Figure 8, the group DG-1-5 exhibits the best CNR and a resolution close to that of the TGI within the DG-1 group. Similarly, for the DG-5 and DG-7 groups, the best CNR close to the TGI resolution can be found in the groups DG-5-3, -4 and DG-7-2, -3, respectively. Regarding the DG-2, DG-6, and DG-8 groups, the mean speckle size step is 25.40 \(\upmu\)m within the speckle size range from 16.5 \(\upmu\)m to 550 \(\upmu\)m. We only consider resolutions higher than 1.0 in this case. The group DG-2-5 shows the best CNR but with a lower resolution. Generally, the group DG-6-2 exhibits higher CNR and better resolution, followed by the group DG-2-2, -3, and DG-8-1, -2.