This is an amended version of simple_take.c.
The files below are all in the directory /opt/EDTpdv/hartmann/src
* An example program to show usage of EDT PCI DV library to acquire and
* optionally save single or multiple images from devices connected to EDT
* high speed digital video interface such as the PCI DV C-Link or PCI DV
* FOX / RCX.
* Provided as a starting point example for adding digital video acquisition
* to a user application. Includes optimization strategies that take
* advantage of the EDT ring buffer library subroutines for pipelining image
function defocus = get_defocus(centroids)
% a function to extract the defocus of the gradient field
% 'centroids' structure
% centroids.image_background_level - the background intensity of an image
% with no illumination on it
% .spot_radius - the radius of a hartmann spot
% .spot_threshold_level - the minimum intensity of pixels used to