This plugin fits the data along the z axis (as obtained with Image>Stacks>Plot z axis profile) for each (x,y) pixel of a stack and creates a new stack with the fit results.
Fit function for z profiles
Use previous pixel for initial fit params
a, b, c,… are the fit parameters.
R2is the R squared value, the coefficient of determination.
D2is the sum of squared residuals.
vto specify the function result.
a, -b/(2*c), R2'
if (a>0) v=sqrt(a); else v=-sqrt(-a);, b
Fitting a 512*512*10 stack with 'Exponential with Offset' needs about a minute on a core i7-6700 (this fit has effectively only one parameter, the two other parameters are calculated directly via linear regression). There is no parallelization except for the parallelization of the ImageJ Minimizer, which uses two threads in parallel to search for minima.