Reconstruction artifacts caused by signals from uncalibrated areas. Two tubes filled with blood were placed on the imaging surface. While Tube 1 served as the control without flow, blood flowed through Tube 2 during widefield measurements. (a) Calibration image of the two tubes. Norm., normalized. Scale bar, 2 mm. (b) Reconstructed widefield images with Tube 1 uncalibrated. Signals from both tubes were captured in widefield imaging. The reconstruction artifacts are marked by a green ellipse. (c) Space-time domain plot of pixels along the axis of Tube 2 in (b), revealing the reconstruction artifacts, marked by a green ellipse. (d) Reconstructed widefield images with both tubes calibrated, showing no artifacts. (e) Space-time domain plot of pixels along the axis of Tube 2 in (d), illustrating a correct reconstruction. Scale bars in b–e, 1 mm. Images in this figure are adapted from ref. 10.