Fig. 1. One-dimensional Gaussian function

Fig. 2. Gaussian function standard deviation varying with gray difference. (a) Theoretical simulation results; (b) experimental verification results

Fig. 3. Edge operators (G_x presents gradient in x direction, and G_y presents gradient in y direction). (a) Sobel operator; (b) Robert operator

Fig. 4. Edge computing images. (a) Lena image; (b) Sobel edge image; (c) Robert edge image; (d) Sobel-Robert edge image

Fig. 5. Haar discrete wavelet decomposition principle

Fig. 6. Wavelet transform images. (a) LL (texture information of the image); (b) LH (horizontal contour of the image); (c) HL (vertical contour of the image); (d) HH (45°and 135° contours of the image)

Fig. 7. Image matrix block decomposition

Fig. 8. Schematic of parallel confocal measurement principle based on DMD

Fig. 9. Verification of sample. (a) Mirror; (b) lattice light

Fig. 10. DB-FEM axial resolution diagram

Fig. 11. Comparison of defocusing evaluation results of uniform plane sample series obtained by DB-FEM and 8 commonly used focusing evaluation functions. (a) Camera exposure time of 2 ms; (b) camera exposure time of 1 ms (camera exposure time affects maximum image gray value)

Fig. 12. Test sample (region 1 is without step change zone, and region 2 contains large step change zone)

Fig. 13. Schematic of layer scanning. (a) Region 1; (b) region 2

Fig. 14. Comparison of experimental data. (a) No step change; (b) large step change