load_image.m.svn-base

fast marching method

function M = load_image(type, n, options)

% load_image - load benchmark images.
%
%   M = load_image(name, n, options);
%
%   name can be:
%   Synthetic images:
%       'chessboard1', 'chessboard', 'square', 'squareregular', 'disk', 'diskregular', 'quaterdisk', '3contours', 'line',
%       'line_vertical', 'line_horizontal', 'line_diagonal', 'line_circle',
%       'parabola', 'sin', 'phantom', 'circ_oscil',
%       'fnoise' (1/f^alpha noise).
%   Natural images:
%       'boat', 'lena', 'goldhill', 'mandrill', 'maurice', 'polygons_blurred', or your own.
%   
%   Copyright (c) 2004 Gabriel Peyre

if nargin<2
    n = 512;
end
options.null = 0;

type = lower(type);

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% parameters for geometric objects
eta = 0.1;              % translation
gamma = 1/sqrt(2);      % slope
if isfield( options, 'eta' )
    eta = options.eta;
end
if isfield( options, 'gamma' )
    eta = options.gamma;
end
if isfield( options, 'radius' )
    radius = options.radius;
end
if isfield( options, 'center' )
    center = options.center;
end
if isfield( options, 'center1' )
    center1 = options.center1;
end


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% for the line, can be vertical / horizontal / diagonal / any
if strcmp(type, 'line_vertical')
    eta = 0.5;              % translation
    gamma = 0;      % slope
elseif strcmp(type, 'line_horizontal')
    eta = 0.5;              % translation
    gamma = Inf;      % slope
elseif strcmp(type, 'line_diagonal')
    eta = 0;              % translation
    gamma = 1;      % slope
end


%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% for some blurring
sigma = 0;
if isfield(options, 'sigma')
    sigma = options.sigma;
end

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
switch lower(type)
    case {'letter-x' 'letter-v' 'letter-z' 'letter-y'}
        if isfield(options, 'radius')
            r = options.radius;
        else
            r = 10;
        end
        M = create_letter(type(8), r, n);
        
    case 'l'
        r1 = [.1 .1  .3 .9];
        r2 = [.1 .1 .9 .4];
        M = double( draw_rectangle(r1,n) | draw_rectangle(r2,n) );
        
    case 'ellipse'
        c1 = [0.15 0.5];
        c2 = [0.85 0.5];
        if isfield(options, 'eccentricity')
            eccentricity = options.eccentricity;
        else
            eccentricity = 1.3;
        end
        x = linspace(0,1,n);
        [Y,X] = meshgrid(x,x);
        d = sqrt((X-c1(1)).^2 + (Y-c1(2)).^2) + sqrt((X-c2(1)).^2 + (Y-c2(2)).^2);
        M = double( d<=eccentricity*sqrt( sum((c1-c2).^2) ) );
    case 'ellipse-thin'
        options.eccentricity = 1.06;
        M = load_image('ellipse', n, options);
    case 'ellipse-fat'
        options.eccentricity = 1.3;
        M = load_image('ellipse', n, options);
        
    case 'square-tube'
        if isfield(options, 'tube_width')
            w = options.tube_width;
        else
            w = 0.06;
        end
        c1 = [.25 .5];
        c2 = [.75 .5];
        r1 = [c1 c1] + .18*[-1 -1 1 1];
        r2 = [c2 c2] + .18*[-1 -1 1 1];        
        r3 = [c1(1)-w c1(2)-w c2(1)+w c2(2)+w];
        M = double( draw_rectangle(r1,n) | draw_rectangle(r2,n) | draw_rectangle(r3,n) );
    case 'square-tube-1'
        options.tube_width = 0.03;
        M = load_image('square-tube', n, options);
    case 'square-tube-2'
        options.tube_width = 0.06;
        M = load_image('square-tube', n, options);
    case 'square-tube-3'
        options.tube_width = 0.09;
        M = load_image('square-tube', n, options);
    case 'polygon'
        if isfield(options, 'nb_points')
            nb_points = options.nb_points;
        else
            nb_points = 9;
        end
        if isfield(options, 'scaling')
            scaling = options.scaling;
        else
            scaling = 1;
        end
        theta = sort( rand(nb_points,1)*2*pi );
        radius = scaling*rescale(rand(nb_points,1), 0.1, 0.93);        
        points = [cos(theta) sin(theta)] .* repmat(radius, 1,2);
        points = (points+1)/2*(n-1)+1; points(end+1,:) = points(1,:);        
        M = draw_polygons(zeros(n),0.8,{points'});
        [x,y] = ind2sub(size(M),find(M));
        p = 100; m = length(x);
        lambda = linspace(0,1,p);
        X = n/2 + repmat(x-n/2, [1 p]) .* repmat(lambda, [m 1]);
        Y = n/2 + repmat(y-n/2, [1 p]) .* repmat(lambda, [m 1]);
        I = round(X) + (round(Y)-1)*n;
        M = zeros(n); M(I) = 1;
    case 'polygon-8'
        options.nb_points = 8;
        M = load_image('polygon', n, options);
    case 'polygon-10'
        options.nb_points = 8;
        M = load_image('polygon', n, options);
    case 'polygon-12'
        options.nb_points = 8;
        M = load_image('polygon', n, options);
    case 'pacman'
        if isfield(options, 'theta')
            theta = options.theta;
        else
            theta = 30 * 2*pi/360;
        end
        options.radius = 0.45;
        M = load_image('disk', n, options);        
        x = linspace(-1,1,n);
        [Y,X] = meshgrid(x,x);
        T =atan2(Y,X);
        M = M .* (1-(abs(T)<theta/2));
    case 'square-hole'
        options.radius = 0.45;
        M = load_image('disk', n, options); 
        options.scaling = 0.5;
        M = M - load_image('polygon-10', n, options); 
        
    case 'grid-circles'
        if isempty(n)
            n = 256;
        end
        if isfield(options, 'frequency')
            f = options.frequency;
        else
            f = 30;
        end
        if isfield(options, 'width')
            eta = options.width;
        else
            eta = 0.3;
        end
        x = linspace(-n/2,n/2,n) - round(n*0.03);
        y = linspace(0,n,n);
        [Y,X] = meshgrid(y,x);
        R = sqrt(X.^2+Y.^2);
        theta = 0.05*pi/2;
        X1 = cos(theta)*X+sin(theta)*Y;
        Y1 = -sin(theta)*X+cos(theta)*Y;
        A1 = abs(cos(2*pi*R/f))<eta;
        A2 = max( abs(cos(2*pi*X1/f))<eta, abs(cos(2*pi*Y1/f))<eta );

        M = A1;
        M(X1>0) = A2(X1>0);
        
    case 'chessboard1'
        x = -1:2/(n-1):1;
        [Y,X] = meshgrid(x,x);
        M = (2*(Y>=0)-1).*(2*(X>=0)-1);
        
    case 'chessboard'
        if ~isfield( options, 'width' )
            width = round(n/16);
        else
            width = options.width;
        end
        [Y,X] = meshgrid(0:n-1,0:n-1);
        M = mod( floor(X/width)+floor(Y/width), 2 ) == 0;
        
    case 'square'
        if ~isfield( options, 'radius' )
            radius = 0.6;
        end
        x = -1:2/(n-1):1;
        [Y,X] = meshgrid(x,x);
        M = max( abs(X),abs(Y) )<radius;
        
    case 'squareregular'
        M = rescale(load_image('square',n,options));
        if not(isfield(options, 'alpha'))
            options.alpha = 3;
        end
        S = load_image('fnoise',n,options);
        M = M + rescale(S,-0.3,0.3); 
        
    case 'regular1'
        options.alpha = 1;
        M = load_image('fnoise',n,options);
    case 'regular2'
        options.alpha = 2;
        M = load_image('fnoise',n,options);
    case 'regular3'
        options.alpha = 3;
        M = load_image('fnoise',n,options);
        
    case 'sparsecurves'
        options.alpha = 3;
        M = load_image('fnoise',n,options);
        M = rescale(M);
        ncurves = 3;
        M = cos(2*pi*ncurves);
               
    case 'square_texture'
        M = load_image('square',n);
        M = rescale(M);
        % make a texture patch
        x = linspace(0,1,n);
        [Y,X] = meshgrid(x,x);
        theta = pi/3;
        x = cos(theta)*X + sin(theta)*Y;
        c = [0.3,0.4]; r = 0.2;
        I = find( (X-c(1)).^2 + (Y-c(2)).^2 < r^2 );
        eta = 3/n; lambda = 0.3;
        M(I) = M(I) + lambda * sin( x(I) * 2*pi / eta ); 
        
        
    case 'oscillatory_texture'
        x = linspace(0,1,n);
        [Y,X] = meshgrid(x,x);
        theta = pi/3;
        x = cos(theta)*X + sin(theta)*Y;
        c = [0.3,0.4]; r = 0.2;
        I = find( (X-c(1)).^2 + (Y-c(2)).^2 < r^2 );
        eta = 3/n; lambda = 0.3;
        M = sin( x * 2*pi / eta ); 
        
    case {'line', 'line_vertical', 'line_horizontal', 'line_diagonal'}
        x = 0:1/(n-1):1;
        [Y,X] = meshgrid(x,x);
        if gamma~=Inf
            M = (X-eta) - gamma*Y < 0;
        else
            M = (Y-eta) < 0;
        end
        
    case 'grating'
        x = linspace(-1,1,n);
        [Y,X] = meshgrid(x,x);
        if isfield(options, 'theta')
            theta = options.theta;
        else
            theta = 0.2;
        end
        if isfield(options, 'freq')
            freq = options.freq;
        else
            freq = 0.2;
        end
        X = cos(theta)*X + sin(theta)*Y;
        M = sin(2*pi*X/freq);
        
    case 'disk'
        if ~isfield( options, 'radius' )
            radius = 0.35;
        end
        if ~isfield( options, 'center' )
            center = [0.5, 0.5];    % center of the circle
        end
        x = 0:1/(n-1):1;
        [Y,X] = meshgrid(x,x);
        M = (X-center(1)).^2 + (Y-center(2)).^2 < radius^2;
        
        
    case 'diskregular'
        M = rescale(load_image('disk',n,options));
        if not(isfield(options, 'alpha'))
            options.alpha = 3;
        end
        S = load_image('fnoise',n,options);
        M = M + rescale(S,-0.3,0.3); 
        
    case 'quarterdisk'
        if ~isfield( options, 'radius' )
            radius = 0.95;
        end
        if ~isfield( options, 'center' )
            center = -[0.1, 0.1];    % center of the circle
        end
        x = 0:1/(n-1):1;
        [Y,X] = meshgrid(x,x);
        M = (X-center(1)).^2 + (Y-center(2)).^2 < radius^2;
        
    case 'fading_contour'
        if ~isfield( options, 'radius' )
            radius = 0.95;
        end
        if ~isfield( options, 'center' )
            center = -[0.1, 0.1];    % center of the circle
        end
        x = 0:1/(n-1):1;
        [Y,X] = meshgrid(x,x);
        M = (X-center(1)).^2 + (Y-center(2)).^2 < radius^2;
        theta = 2/pi*atan2(Y,X);
        h = 0.5;
        M = exp(-(1-theta).^2/h^2).*M;
        
    case '3contours'        
        radius = 1.3;
        center = [-1, 1];
        radius1 = 0.8;
        center1 = [0, 0];
        x = 0:1/(n-1):1;
        [Y,X] = meshgrid(x,x);
        f1 = (X-center(1)).^2 + (Y-center(2)).^2 < radius^2;
        f2 = (X-center1(1)).^2 + (Y-center1(2)).^2 < radius1^2;
        M = f1 + 0.5*f2.*(1-f1);
        
    case 'line_circle'

        gamma = 1/sqrt(2);

        x = linspace(-1,1,n);
        [Y,X] = meshgrid(x,x);
        M1 = double( X>gamma*Y+0.25 );
        M2 = X.^2 + Y.^2 < 0.6^2;
        M = 20 + max(0.5*M1,M2) * 216;
        
    case 'fnoise'
        
        % generate an image M whose Fourier spectrum amplitude is 
        %   |M^(omega)| = 1/f^{omega}