focus-stack is an application for fast and easy focus stacking.

It takes a series of photographs captured from the same location but
a different focus distances and then combines them to create a single
photograph so that the complete subject is in focus. This is commonly
called extended depth of field, or focus stacking. Typical use is for
microscope photography where it is difficult to obtain large enough
depth of field to cover the whole subject. The focus stacking
algorithm used was invented and first described in "Complex Wavelets
for Extended Depth-of-Field: A New Method for the Fusion of
Multichannel Microscopy Images" by B. Forster, D. Van De Ville, J.
Berent, D. Sage and M. Unser. The application also uses multiple
algorithms from OpenCV library. Most importantly, findTransformECC
is used to align the source images.