Fig. 1. Principle of snapshot diffractive spectral imaging system. (a) Rotationally symmetric DOE structure; (b) schematic diagram of light propagation in diffractive-refractive hybrid system; (c) flowchart of spectral image reconstruction algorithm; (d) flowchart of diffractive image degradation and reconstruction

Fig. 2. DUF-based diffractive spectral image reconstruction algorithm and its sub-modules. (a) Iteration flowchart of DUF; (b) DST; (c) HSAB; (d) FFN; (e) HS-MSA

Fig. 3. Schematic diagrams of surface error. (a) Without surface error; (b) with surface error; (c) trend of diffraction efficiency of DOE with absolute value of random surface error

Fig. 4. Graphic structure location error in actual fabrication. (a) Surface of DOE under optical microscope; (b) local magnification of surface

Fig. 5. Alignment error of optical system. (a) Light propagation schematic; (b) PSF of selected spectral bands

Fig. 6. Defocusing error of optical system. (a) Light propagation diagram; (b) PSF of selected spectral bands

Fig. 7. Synthesizing haze in spectral datasets. (a) RGB visualization image of spectral data; (b) depth matrix predicted by Marigold; (c) spectral data with haze

Fig. 8. Designed DOE. (a) Surface of DOE; (b) PSF images of partial spectral bands

Fig. 9. Simulation reconstruction results. (a) Ground truths; (b) diffracted degraded images; (c) visualization of reconstructed spectral images; (d) spectral images from 400 to 700 nm

Fig. 10. Comparison of reconstruction results of 5 networks for a specific scene. (a) Ground truths; (b) EDSR; (c) MIRNet; (d) Restormer; (e) Res-Unet; (f) DUF-DST; (g) spectral curves in region ①; (h) spectral curves in region ②

Fig. 11. Diffractive degraded images with error or noise (up) and its reconstruction results (down). (a) Without error; (b) random surface error; (c) graphic structure location error; (d) alignment error; (e) defocus error; (f) sensor noise; (g) environmental haze noise; (h) ground truth

Fig. 12. Comparison of reconstruction results before and after error optimization. (a) Ground truth; (b) without considering error and without error; (c) without considering error but with error; (d) considering error but without error; (e) considering error and with error

Fig. 13. Setup of diffractive spectral imaging experiment. (a) Overall optical path; (b) fabricated DOE; (c) imaging system; (d) test object

Fig. 14. Results of indoor imaging experiments. (a) Captured images; (b) visualization of reconstructed spectral images; (c) spectral images from 400 to 700 nm

Fig. 15. Comparison of reconstruction results of 5 spectral image reconstruction networks for a specific scene. (a) EDSR; (b) MIRNet; (c) Restormer; (d) Res-Unet; (e) DUF-DST; (f) spectral curves in region ①; (g) spectral curves in region ②

Fig. 16. Results of outdoor imaging experiments. (a) Captured images; (b) visualization of reconstructed spectral images; (c) spectral images from 400 to 700 nm

Fig. 17. Comparison of reconstruction results of 5 spectral image reconstruction networks for a specific scene. (a) EDSR; (b) MIRNet; (c) Restormer; (d) Res-Unet; (e) DUF-DST; (f) spectral reflectance of green leaves of different plants^[33]; (g) spectral curves in region ①

Fig. 18. Results of outdoor dehazing imaging experiments. (a) Captured images; (b) results obtained by reconstruction network without dehazing; (c) results obtained by reconstruction network with dehazing; (d) spectral images from 400 to 700 nm