Fig. 6

Overcoming the parameter estimation obstacles encountered by the Wiener-based SIM algorithms with direct-SIM. a Equivalent wide-field image of 100-nm fluorescent beads (left), and the SR image reconstructed by fairSIM (right). b SR image reconstructed by direct-SIM. c Comparison of the pattern periods determined by fairSIM with the calibration values of the imaging system. d Magnified images of the green boxes in (a, b), and the direct-SIM image (in red) is overlaid with the equivalent wide-field image (in blue) and fairSIM image (in green), for comparison. e Cross-correlation map obtained by fairSIM. Symbol \({\varvec{k}}_{ex}\) denotes the illumination pattern wave vector, and \({\varvec{k}}_{em}\) denotes the cutoff frequency of the microscope system. f Comparison of the pattern periods determined by fairSIM with the calibration values of the imaging system. g Equivalent wide-field image of “grid” patterns in Argolight slide acquired on DeltaVision OMX (left), and the SR images reconstructed by fairSIM (middle) and direct-SIM (right), respectively. h Magnified images of the green box in (g), and the SR image of direct-SIM (in red) is overlaid with the equivalent wide-field image (in blue) and fairSIM image (in green), for comparison. i Intensity profiles along the magenta lines in (h). Scale bars, 1 μm in (a, b, h), 0.2 μm in (d) and 8 μm in (g)