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GREIT algorithm candidates

Each GREIT algorithm candidate function must be of the following form:
function [img,map]= ALG_NAME( ref_meas, reconst_meas )
where
    img 32×32×N conductivity change image representing the N measurement instants
    map 32×32 vector indicating which pixels are inside the medium (=1) and which are outside (=0).
    ref_meas 208×1 measurement vector representing the background conductivity
    img 208×N measurement vector representing the N measurement instants

Difference Imaging

EIT difference imaging calculates a change in conductivity (Δσ) from the change in measurmements
vi2vi1
where vi2 is the ith component of the measurement frame after the change, and vi1 is the ith component of the measurement frame before the change.

A difference imaging algorithm may look like this example:

function img= ALG_NAME( ref_meas, reconst_meas )

   load ReconstMatrix_from_ALG_NAME RM;

   % Expand ref_meas to the full size of reconst_meas
   num_meas = size(reconst_meas,2);
   ref_meas = ref_meas * ones(1,num_meas);
   dv = reconst_meas - ref_meas;

   % reconst image
   ds = RM*dv;

   img= reshape(ds, 32,32,num_meas);

Normalized Difference Imaging

EIT normalized difference imaging calculates a change in conductivity (Δσ) from a normalized change in measurmements
( vi2vi1 ) / vi1

A normalized difference imaging algorithm may look like this example:

function img= ALG_NAME( ref_meas, reconst_meas )

   load ReconstMatrix_from_ALG_NAME RM;

   % Expand ref_meas to the full size of reconst_meas
   num_meas = size(reconst_meas,2);
   ref_meas = ref_meas * ones(1,num_meas);
   dv = ( reconst_meas - ref_meas ) ./ ref_meas; % CHANGE IS HERE:

   % reconst image
   ds = RM*dv;

   img= reshape(ds, 32,32,num_meas);

Comments

Some things to note about GREIT algorithm candidates:
  • An algorithm accepts no parameters. There is no place to enter a regularization hyperparameter, for example. This is intentional, since each GREIT algorithm is supposed to be completely stand alone. Different variants of algorithms should have different names.
  • Algorithms do not accept shape information. Again, this is intentional, since GREIT algorithms for different shapes (adult thorax, cylindrical tank, etc.) are considered to be different algorithms.

Algorithm examples

Some examples of GREIT evaluation functions are:

Last Modified: $Date: 2017-02-28 13:12:08 -0500 (Tue, 28 Feb 2017) $ by $Author: aadler $