SLIM Curve is a curve fitting library used for Fluorescent Lifetime Imaging or FLIM and Spectral Lifetime Imaging or SLIM. It is developed by Paul Barber and the Advanced Technology Group at the Cancer Research UK and Medical Research Council Oxford Institute for Radiation Oncology, University of Oxford, as well as the Laboratory for Optical and Computational Instrumentation at the University of Wisconsin-Madison. SLIM Curve is used for FLIM functionality in his TRI2 (Time Resolved Imaging) software. SLIM Curve is used for FLIM functionality in the Advanced Technology Group's Time Resolved Imaging (TRI2) software, as well as in the SLIM Curve plugin for ImageJ.
For exponential lifetime fitting there are two core algorithms within SLIM Curve:
- A triple integral method that does a very fast estimate of a single exponential lifetime component.
- The second is a Levenberg-Marquardt algorithm or LMA that uses an iterative, least-squares-minimization approach to generate a fit. This works with single, double and triple exponential models, as well as stretched exponential.
There is also code to perform 'global' analysis over a number of signals simultaneously (e.g. over an image), where the lifetimes can be considered constant across the data set, but the amplitudes are allowed to vary for each signal. There is also a completely generic global analysis function. A third algorithm is available to perform phasor analysis.
In addition there is a non-negative linear least squares algorithm that is useful for spectral unmixing in SLIM.
The code is written in C89 compatible C and is thread safe for fitting multiple
pixels concurrently. Several files are provided as wrappers to call this
library from Java code:
.h provide a subset of function
calls used by the ImageJ plugin; these may be invoked directly from Java using
JNA. In addition there is a Java CurveFitter project that provides a wrapper to
the SLIM Curve code. This invokes the C code using JNI, with
src- source files
src/main/c- The source files for the SLIM Curve library
src/slim-curve-cmd/c- The source files for the standalone executable wrapper for the library
src/slim-curve-cmd/c/doc- API documentaion
test_files- dat and ini settings file for testing
To build the standalone program using CMake and gcc under Linux:
Create a build folder, and cd to it
mkdir build cd build
Copy the executable to the
test_filesfolder for convenience
cp slim-curve-cmd ../test_files
Run the program with the test files
cd ../test_files ./slim-curve-cmd test.ini transient.dat