  We present a versatile and fast MATLAB program (UmUTracker) that
automatically detects and tracks particles by analyzing video sequences
acquired by either light microscopy or digital in-line holographic microscopy.
Our program detects the 2D lateral positions of particles with an algorithm
based on the isosceles triangle transform, and reconstructs their 3D axial
positions by a fast implementation of the Rayleigh-Sommerfeld model using a
radial intensity profile. To validate the accuracy and performance of our
program, we first track the 2D position of polystyrene particles using bright
field and digital holographic microscopy. Second, we determine the 3D particle
position by analyzing synthetic and experimentally acquired holograms. Finally,
to highlight the full program features, we profile the microfluidic flow in a
100 micrometer high flow chamber. This result agrees with computational fluid
dynamic simulations. On a regular desktop computer UmUTracker can detect,
analyze, and track multiple particles at 5 frames per second for a template
size of 201 x 201 in a 1024 x 1024 image. To enhance usability and to make it
easy to implement new functions we used object-oriented programming. UmUTracker
is suitable for studies related to: particle dynamics, cell localization,
colloids and microfluidic flow measurement.
