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26 lines
826 B
Matlab
26 lines
826 B
Matlab
function [H,ori,sf]=image_hartley_subspace(sz,border,span,step)
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hsz=floor(sz/2);
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if nargin<3 | isempty(span), span=hsz; end
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if nargin<4 | isempty(step), step=1; end
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num=length([-span:step:span])^2
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k=0;
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for ky=-span:step:span,
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for kx=-span:step:span,
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k=k+1;
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h=hartley_image(kx,ky,sz,border);
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H(:,:,k)=0.5+0.5.*h./sqrt(2); %positive, rescaled to be between 0 and 1
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H(:,:,num+k)=0.5+0.5.*-h./sqrt(2);;%negative, rescaled to be between 0 and 1
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ori(k)=atand(kx/ky); %orientation of stimulus in degrees
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ori(num+k)=ori(k);
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sf(k)=sqrt(kx^2+ky^2)./sz; %spatial frequency of stimulus in cycles/pixel
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sf(num+k)=sf(k);
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end
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end
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function H=hartley_image(kx,ky,sz,border)
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imsize=sz+2*border;
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[x y]=meshgrid(-fix(imsize/2):fix(imsize/2),fix(-imsize/2):fix(imsize/2));
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arg=(2*pi.*(kx.*x+ky.*y))./sz;
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H=sin(arg)+cos(arg);
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