Fig. 1
Superresolution mechanism and flow chart of direct-SIM. a The superresolution mechanism of spatial domain reconstruction of direct-SIM is equivalent to the convolution result of the separated -1st- and + 1st-order harmonics. Symbol \(\otimes\) is the convolution operator. “Line” patterns in Argolight slide were imaged by DeltaVision OMX with 50 ms exposure. b The flow chart of direct-SIM consists of four steps: preprocessing [involving removal of background fluorescence, and enhancement of the equivalent modulation depths via RL deconvolution; in this case, the equivalent modulation depths are 0.312, 0.378, 0.495 (without preprocessing), and 0.572, 0.699, 0.772 (preprocessing)], spatial domain direct reconstruction of the initial image through the RMS-form SR model, nonlinear spectrum optimization to improve image contrast, and RL deconvolution to reconstruct the final SR image. Scale bars, 2 μm in (a), 3 μm in (b)