Fig. 3

Improving imaging resolution of microtubule in COS-7 cells by direct-SIM. a Equivalent wide-field image is shown in the left, and the SR images reconstructed by HiFi-SIM and direct-SIM, respectively. Upper-right corner shows the corresponding reconstructed spectrum. b Magnified images of the white box in (a). c Intensity profiles along the white lines in (b). d Magnified images of the magenta box in (a), and the direct-SIM image (in green) is overlaid with the HiFi-SIM image (in magenta), for comparison. e Magnified images of the green box in (a), and the direct-SIM image (in green) is overlaid with the HiFi-SIM image (in magenta), for comparison. f Map of the illumination pattern modulation depth of different sub-regions (sub-block: 64 pixels*64 pixels) in the raw data was determined by the parameter estimation method of HiFi-SIM. g Error map of direct-SIM obtained by SQUIRREL analysis. Scale bars, 6 μm in (a), 0.5 μm in (b) and 2 μm in (d, e)