function [c,Ls]=dgt2(f,g1,p3,p4,p5,p6)
%DGT2 2-D Discrete Gabor transform
% Usage: c=dgt2(f,g,a,M);
% c=dgt2(f,g1,g2,[a1,a2],[M1,M2]);
% c=dgt2(f,g1,g2,[a1,a2],[M1,M2],[L1,L2]);
% [c,Ls]=dgt2(f,g1,g2,[a1,a2],[M1,M2]);
% [c,Ls]=dgt2(f,g1,g2,[a1,a2],[M1,M2],[L1,L2]);
%
% Input parameters:
% f : Input data, matrix.
% g,g1,g2 : Window functions.
% a,a1,a2 : Length of time shifts.
% M,M1,M2 : Number of modulations.
% L1,L2 : Length of transform to do
%
% Output parameters:
% c : array of coefficients.
% Ls : Original size of input matrix.
%
% DGT2(f,g,a,M) will calculate a separable two-dimensional discrete
% Gabor transformation of the input signal f with respect to the window
% g and parameters a and M.
%
% For each dimension, the length of the transform will be the smallest
% possible that is larger than the length of the signal along that dimension.
% f will be appropriately zero-extended.
%
% DGT2(f,g,a,M,L) computes a Gabor transform as above, but does
% a transform of length L along each dimension. f will be cut or
% zero-extended to length L before the transform is done.
%
% [c,Ls]=DGT2(f,g,a,M) or [c,Ls]=DGT2(f,g,a,M,L) additionally returns
% the length of the input signal f. This is handy for reconstruction:
%
% [c,Ls]=dgt2(f,g,a,M);
% fr=idgt2(c,gd,a,Ls);
%
% will reconstruct the signal f no matter what the size of f is, provided
% that gd is a dual window of g.
%
% DGT2(f,g1,g2,a,M) makes it possible to use a different window along the
% two dimensions.
%
% The parameters a, M, L and Ls can also be vectors of length 2.
% In this case the first element will be used for the first dimension
% and the second element will be used for the second dimension.
%
% The output c has 4 or 5 dimensions. The dimensions index the
% following properties:
%
% 1. Number of translation along 1st dimension of input.
%
% 2. Number of channel along 1st dimension of input
%
% 3. Number of translation along 2nd dimension of input.
%
% 4. Number of channel along 2nd dimension of input
%
% 5. Plane number, corresponds to 3rd dimension of input.
%
% See also: dgt, idgt2, gabdual
%
% Url: http://ltfat.github.io/doc/gabor/dgt2.html
% Copyright (C) 2005-2023 Peter L. Soendergaard <peter@sonderport.dk> and others.
% This file is part of LTFAT version 2.6.0
%
% This program is free software: you can redistribute it and/or modify
% it under the terms of the GNU General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% This program is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU General Public License for more details.
%
% You should have received a copy of the GNU General Public License
% along with this program. If not, see <http://www.gnu.org/licenses/>.
complainif_argnonotinrange(nargin,4,6,mfilename);
L=[];
if prod(size(p3))>2
% Two windows was specified.
g2=p3;
a=p4;
M=p5;
if nargin==6
L=p6;
end;
else
g2=g1;
a=p3;
M=p4;
if nargin==5
L=p5;
end;
end;
if isempty(L)
L1=[];
L2=[];
else
L1=L(1);
L2=L(2);
end;
% Expand 'a' and M if necessary to two elements
a=bsxfun(@times,a,[1 1]);
M=bsxfun(@times,M,[1 1]);
Ls=size(f);
Ls=Ls(1:2);
c=dgt(f,g1,a(1),M(1),L1);
c=dgt(c,g2,a(2),M(2),L2,'dim',3);