MATLAB function for drifting grating (2D sine wave)

get_drifting_grating.m

function imgs = get_drifting_grating( n_frames, rec, tilt, sf, drift_speed, plot_option )
%% MATLAB function for drifting grating (2D sine wave)
% Usage:  
%     imgs = get_drifting_grating( n_frames, rec, tilt, sf, drift_speed, plot_option )
%     ex) imgs = get_drifting_grating( 60, 500, 30, .01, 5, 1 );
%     ex) imgs = get_drifting_grating();
% 
% written by Hio-Been Han, 2020-02-22
% hiobeen.han@kaist.ac.kr
% 
%% (1) Check arg-in
if nargin < 6, plot_option = 1; 
elseif nargin < 5, drift_speed = 1; 
elseif nargin < 4, sf = .005; 
elseif nargin < 3, tilt = 30; 
elseif nargin < 2, rec = 100; 
elseif nargin < 1, n_frames = 1; 
end

%% (2) Set phase vector
initial_phase = rand*360; % set random initial phase
phases = mod( initial_phase: drift_speed: n_frames*drift_speed+initial_phase, 360);

%% (3) Calculate
x=rec/2; y=rec/2;
[mesh_x, mesh_y] = meshgrid(0:(rec-1), 0:(rec-1));
a=cos(deg2rad(tilt))*sf*360;
b=sin(deg2rad(tilt))*sf*360;
imgs = [];
counter = 0;
for phase = phases(1:end-1)
    counter = counter+1;
    imgs(:,:,counter ) = sin(deg2rad(a*(mesh_x - x) + b*(mesh_y - y)+phase))/2+.5 ;
end

%% (4) Visualization (if specified)
if plot_option
    figure(100); clf;
        colormap gray
    for frameIdx = 1:n_frames
        imagesc(imgs(:,:,frameIdx));
        set(gca,'XTick',[1,rec],'YTick',[1,rec],'LineWidth',2,'Box','off');
        if n_frames>1, title(frameIdx); end
        drawnow;
    end
end

return