## 6 Discussion  
In the current system, the higher the sensitivity of the camera, the higher the dynamic range images that can be captured, which provides more powerful conditions for the reconstruction of the high-resolution image using the FP algorithm. However, under the current conditions of our experimental setup, insufficient sampling of low-resolution images affects the quality of the reconstructed image and fails to recover even small resolution features. In addition, we believe that changing to a larger object or a different camera sensor may effectively solve this problem.  
In addition, we find that the stripes in the diagonal direction can recover better, which may be caused by the imaging capability of the imaging lens. As shown in Figure 14, the modulation transfer function (MTF) of the imaging lens has different values in the S and T directions. Therefore, in a certain direction, the spatial frequency can pass well. Verification of this hypothesis will be carried out in follow-up work [15]. The Figure 14 is only a sketch map, and we can see that the imaging ability of the lens is different in different directions.  
\begin{table}
\begin{tabular}{c c c c} \hline \multicolumn{2}{c}{**Full-Frame Reconstruction**} & \multicolumn{2}{c}{**Partition Reconstruction**} \\ \hline \multirow{4}{*}{Resolution} & Step with 4.5 μm & Step with 2 μm & Step with 2 μm \\  & Group 9 & Group 17 & Group 25 \\  & 101 μm, 4.95 lp/mm & 63.5 μm, 7.87 lp/mm & 40 μm, 12.5 lp/mm \\ \cline{1-1} Signal to noise ratio (SNR) & 25.6 dB & 28.6 dB & 32.5 dB \\ \hline \end{tabular}
\end{table}
Table 1: Comparison of the experimental results.  
Figure 13: Reconstruction results by partition reconstruction on real datasets with scanning step 2 mm when capturing corresponding LR images. (**a**) the central raw image; (**a1**) the central raw image with partition reconstruction; (**b**) the high-resolution image of (**a1**); (**b1**) the zoomed-in intensity image of Group 25; and we also show the synthetic aperture and the phase details in (**c,d**) respectively.  
Now, while we addressed the image misalignment arising from camera movement, for far-field FP imaging, the slight position errors in the camera's movement will change the spectrum redundancy information, and the imaging contrast may not be significantly reduced. The missing information in the Fourier plane causes obvious errors in the image reconstruction process, which may result in poor intensity images in a certain direction. Next, we plan to address this deficiency, improve the experimental conditions, and strengthen phase retrieval algorithm research to obtain higher-resolution complex images [16; 17; 18; 19; 20; 21].  
Another consideration that must be addressed is the relationship between the performance of the proposed technique and the associated hardware [22; 23; 24]. For example, the stripes in certain directions cannot be correctly resolved on the basis of the orientation characteristics of the imaging lens. Thus, we plan to improve the experimental conditions, replace the camera, and study various interference components of the system [22].  
Additionally, we will adapt the active coherent illumination imaging system on the basis of the far-field FP imaging mechanism to establish a reflective mathematical model, as well as build a reflective experimental system to realize phase recovery and super-resolution [25; 26; 27; 28]. This can overcome the limitation of the system aperture on spatial resolution improvement in the passive non-coherent imaging system, and thus will demonstrate the potential of this technology in remote sensing applications.