im_shift3.m

function new_im = im_shift3(img, SHIFTX, SHIFTY)
%% Robert's code
%% Reference:  Robert Prevede, Young-Gyu Yoon, Maximilian Hoffmann, Nikita Pak.etc. 
%% "Simultaneous whole-animal 3D imaging of neuronal activity using light-field microscopy " 
%% in Nature Methods VOL.11 NO.7|July 2014.
%% Downloaded from https://www.nature.com/articles/nmeth.2964
eqtol = 1e-10;

xlength = size(img,1);
ylength = size(img,2);

if abs(mod(SHIFTX,1))>eqtol | abs(mod(SHIFTY,1))>eqtol
   error('SHIFTX and SHIFTY should be integer numbers');
end

% if SHIFTX >= xlength | SHIFTY >= ylength,
%    error('SHIFTX  and SHIFTY should be smaller than size(img,1) and size(img,2), respectively');
% end


    
SHIFTX = round(SHIFTX);
SHIFTY = round(SHIFTY);

new_im = zeros(xlength, ylength,size(img,3));

if SHIFTX >=0 & SHIFTY >= 0,
    new_im( (1+SHIFTX:end), (1+SHIFTY:end) ,:) = img( (1:end-SHIFTX), (1:end-SHIFTY) ,:);
elseif SHIFTX >=0 & SHIFTY < 0,
    new_im( (1+SHIFTX:end), (1:end+SHIFTY) ,:) = img( (1:end-SHIFTX), (-SHIFTY+1:end) ,:);
elseif SHIFTX <0 & SHIFTY >= 0,
    new_im( (1:end+SHIFTX), (1+SHIFTY:end) ,:) = img( (-SHIFTX+1:end), (1:end-SHIFTY) ,:);
else
    new_im( (1:end+SHIFTX), (1:end+SHIFTY) ,:) = img( (-SHIFTX+1:end), (-SHIFTY+1:end) ,:);
end


end