Spatial interpolation and temporal filtering’s effects on IR in numerical simulations for two complex phantoms. (a1) Ground truth of a complex initial pressure p0 distribution confined to S1. (a2)–(a4) Reconstructions of the object in (a1) using (a2) UBP, (a3) UBP with SI, and (a4) UBP with TF and SI, respectively. SI, spatial interpolation; TF, temporal filtering. The artifacts in the red-boxed region are caused by spatial aliasing in IR, and they are mainly mitigated by SI. (b1) Comparison of the STDs in the ROIs A–C. (b2) and (b3) Comparisons of the profiles of lines P and Q, respectively, for the three methods. (c1) Ground truth of a complex initial pressure p0 distribution beyond S1. (c2)–(c4) Reconstructions of the object in (c1) using (c2) UBP, (c3) UBP with SI, and (c4) UBP with TF and SI, respectively. The artifacts in the red-boxed region are caused by spatial aliasing in SS and IR, and the artifacts are mitigated by TF and SI. (d1) Comparison of the STDs in the ROIs A–C. (d2) and (d3) Comparisons of the profiles of lines P and Q, respectively, for the three methods. The FWHM of the main lobe at Q was increased from 0.35 mm to 0.48 mm by temporal filtering, while the amplitude was changed from 0.90 to 0.56, respectively.