%TOIMAGE  transforms a spectrum made of 1D functions in an 2D image%% [im,tt,ff] = TOIMAGE(A,f,t,splx,sply) transforms a spectrum made% of 1D functions (e.g., output of "hhspectrum") in an 2D image%% inputs :   - A    : amplitudes of modes (1 mode per row of A)%            - f    : instantaneous frequencies%            - t    : time instants %            - splx : number of columns of the output im (time resolution).%                     If different from length(t), works only for uniform %                     sampling.%            - sply : number of rows of the output im (frequency resolution).% outputs :  - im   : 2D image of the spectrum%            - tt   : time instants in the image%            - ff   : centers of the frequency bins%% Examples : [im,tt,ff] = toimage(A,f);[im,tt] = toimage(A,f,t);[im,tt,ff] = toimage(A,f,sply);%            [im,tt,ff] = toimage(A,f,splx,sply);[im,tt,ff] = toimage(A,f,t,splx,sply);%%% See also%  emd, hhspectrum, disp_hhs%% G. Rilling, last modification 3.2007% gabriel.rilling@ens-lyon.frfunction [im,tt,ff] = toimage(A,f,varargin)DEFSPL = 400;error(nargchk(2,5,nargin));switch nargin  case 2    t = 1:size(A,2);    sply = DEFSPL;    splx = length(t);  case 3    if isscalar(varargin{1})      t = 1:size(A,2);      splx = length(t);      sply = varargin{1};    else      t = varargin{1};      splx = length(t);      sply = DEFSPL;    end  case 4    if isscalar(varargin{1})      t = 1:size(A,2);      sply = varargin{1};      splx = varargin{2};    else      t = varargin{1};      sply = varargin{2};      splx = length(t);    end  case 5    t = varargin{1};    splx = varargin{2};    sply = varargin{3};endif isvector(A)  A = A(:)';  f = f(:)';endif issparse(A) || ~isreal(A) || length(size(A)) > 2   error('A argument must be a real matrix')endif issparse(f) || ~isreal(f) || length(size(f)) > 2  error('f argument must be a real matrix')endif any(size(f)~=size(A))  error('A and f matrices must have the same size')endif issparse(t) || ~isreal(t) || ~isvector(t) || length(t)~=size(A,2)  error('t argument must be a vector and its length must be the number of columns in A and f inputs')endif ~isscalar(splx) || ~isreal(splx) || splx ~= floor(splx) || splx <= 0  error('splx argument must be a positive integer')endif ~isscalar(sply) || ~isreal(sply) || sply ~= floor(sply) || sply <= 0  error('splx argument must be a positive integer')endif any(diff(diff(t))) && splx ~= length(t)  warning('toimage:nonuniformtimeinsants','When splx differs from length(t), the function only works for equally spaced time instants. You may consider reformating your data (using e.g. interpolation) before using toimage.')endf = min(f,0.5);f = max(f,0);indf = round(2*f*(sply-1)+1);indt = repmat(round(linspace(1,length(t),splx)),size(A,1),1);im = accumarray([indf(:),indt(:)],A(:),[sply,splx]);indt = indt(1,:);tt = t(indt);ff = (0:sply-1)*0.5/sply+1/(4*sply);end