Fig. 7: Comparisons with global analysis for bi-exponential decay in FLIM.
From: CASPI: collaborative photon processing for active single-photon imaging
a The ground-truth used for simulating photon transient cubes consists of two invariant lifetimes τ1 = 3 ns and τ2 = 1.5 ns with relative contributions β1 = 0.1, 0.5, 0.9 and β2 = 1 − β1 that vary over the field-of-view. b When estimating the parameters of a multi-exponential decay model, pixel-wise fitting is often unreliable if fewer than 1000 photons are available per pixel. c Global analysis provides better estimation accuracy than pixel-wise fitting by considering all photon transients simultaneously assuming that the lifetimes are spatially invariant. d CASPI can reliably estimate the parameters of a bi-exponential decay model in FLIM even with as few as 200 photons per pixel without the spatial-invariance assumption that global analysis relies on. After applying CASPI, even a pixel-wise fitting provides better estimates than global analysis by 5× in RMSE.
