82 lines
2.6 KiB
Mathematica
82 lines
2.6 KiB
Mathematica
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function [r,g,b] = transformImage_log(A, Ar, Ac, Nrho, Ntheta, Method, Center, Shape)
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% Inputs: A the input image
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% Nrho the desired number of rows of transformed image
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% Ntheta the desired number of columns of transformed image
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% Method interpolation method (nearest,bilinear,bicubic)
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% Center origin of input image
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% Shape output size (full,valid)
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% Class storage class of A
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global rho;
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theta = linspace(0,2*pi,Ntheta+1); theta(end) = [];
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switch Shape
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case 'full'
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corners = [1 1;Ar 1;Ar Ac;1 Ac];
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d = max(sqrt(sum((repmat(Center(:)',4,1)-corners).^2,2)));
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case 'valid'
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d = min([Ac-Center(1) Center(1)-1 Ar-Center(2) Center(2)-1]);
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end
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% minScale = .5;
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% rho = logspace(log10(minScale),log10(d),Nrho)'; % default 'base 10' logspace - play with d to change the scale of the log axis
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% rad_lin = linspace(logb(1,1.044), logb(256,1.044),256)';
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% rho = 0.5.*(1.044.^rad_lin);
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minScale = 1;
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% maxScale = 127;
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% maxScale = 2;
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maxScale = Ar/2-1;
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% rad_lin = linspace(log(minScale), log(maxScale),256)';
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rad_lin = linspace(log(minScale), log(maxScale),Ar)';
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% rad_lin = linspace(logb(1,1.044), logb(127,1.044),256)';
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rho = exp(rad_lin);
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% rho = (1.044.^rad_lin);
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% convert polar coordinates to cartesian coordinates and center
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xx = rho*cos(theta) + Center(1);
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yy = rho*sin(theta) + Center(2);
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if nargout==3
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if strcmp(Method,'nearest'), % Nearest neighbor interpolation
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r=interp2(A(:,:,1),xx,yy,'nearest');
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g=interp2(A(:,:,2),xx,yy,'nearest');
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b=interp2(A(:,:,3),xx,yy,'nearest');
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elseif strcmp(Method,'bilinear'), % Linear interpolation
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r=interp2(A(:,:,1),xx,yy,'linear');
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g=interp2(A(:,:,2),xx,yy,'linear');
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b=interp2(A(:,:,3),xx,yy,'linear');
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elseif strcmp(Method,'bicubic'), % Cubic interpolation
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r=interp2(A(:,:,1),xx,yy,'cubic');
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g=interp2(A(:,:,2),xx,yy,'cubic');
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b=interp2(A(:,:,3),xx,yy,'cubic');
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else
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error(['Unknown interpolation method: ',method]);
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end
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% any pixels outside , pad with black
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mask= (xx>Ac) | (xx<1) | (yy>Ar) | (yy<1);
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r(mask)=0;
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g(mask)=0;
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b(mask)=0;
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else
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if strcmp(Method,'nearest'), % Nearest neighbor interpolation
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r=interp2(A,xx,yy,'nearest');
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elseif strcmp(Method,'bilinear'), % Linear interpolation
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r=interp2(double(A),xx,yy,'linear');
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elseif strcmp(Method,'bicubic'), % Cubic interpolation
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r=interp2(double(A),xx,yy,'cubic');
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else
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error(['Unknown interpolation method: ',method]);
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end
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% any pixels outside warp, pad with black
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mask= (xx>Ac) | (xx<1) | (yy>Ar) | (yy<1);
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r(mask)=0;
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end
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