spectogram.m

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% Anne Urai and Klaus Wimmer, 2016
% anne.urai@gmail.com / kwimmer@clinic.ub.es

function spectogram(inp, cfg)
% FFT spectrum of stimulus
% http://www.gaussianwaves.com/2014/07/how-to-plot-fft-using-matlab-fft-of-basic-signals-sine-and-cosine-waves/

% get the power spectrum
X       = fftshift(abs(fftn(inp)));

% compute correct axes
t   = (0:size(inp,2)) * 1/cfg.frameRate;
x   = ((1:size(inp,1)) - round(size(inp, 1) / 2)) * 1 / cfg.ppd;
f   = 1./(t(2)-t(1))*((1:numel(t))-(numel(t)/2+1))/numel(t);
x   = 1./(x(2)-x(1))*((1:numel(x))-(numel(x)/2+1))/numel(x);

colormap(1-gray);
imagesc(x, f, squeeze(X));
xlabel('Spatial frequency (1/deg)');
ylabel('Temporal frequency (1/s)');
axis([-5 5 -10 10]);
axis ij; % axis image additionally makes square;

end