D Quality of SDD model fitting to tFT-Bcd ratio for different Bcd diffusion coefficients and lifetimes. For each pair of these parameters, the fluorescence correction ε is left as a free parameter for fitting. The colormap is the log of the fitting function (Methods). The white lines correspond to parameter combinations that produce a gradient with a length constant λ=75μm (solid) and λ=95μm (dashed). 