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testpattern.m
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testpattern.m
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%TESTPATTERN Create test images
%
% IM = TESTPATTERN(TYPE, D, ARGS) creates a test pattern image. If D is a
% scalar the image is DxD else D=[W H] the image is WxH. The image is specified by the
% string TYPE and one or two (type specific) arguments:
%
% 'rampx' intensity ramp from 0 to 1 in the x-direction. ARGS is the number
% of cycles.
% 'rampy' intensity ramp from 0 to 1 in the y-direction. ARGS is the number
% of cycles.
% 'sinx' sinusoidal intensity pattern (from -1 to 1) in the x-direction.
% ARGS is the number of cycles.
% 'siny' sinusoidal intensity pattern (from -1 to 1) in the y-direction.
% ARGS is the number of cycles.
% 'dots' binary dot pattern. ARGS are dot pitch (distance between
% centres); dot diameter.
% 'squares' binary square pattern. ARGS are pitch (distance between
% centres); square side length.
% 'line' a line. ARGS are theta (rad), intercept.
%
% Examples::
%
% A 256x256 image with 2 cycles of a horizontal sawtooth intensity ramp:
% testpattern('rampx', 256, 2);
%
% A 256x256 image with a grid of dots on 50 pixel centres and 20 pixels in
% diameter:
% testpattern('dots', 256, 50, 25);
%
% Notes::
% - With no output argument the testpattern in displayed using idisp.
%
% See also IDISP.
% Copyright (C) 1993-2011, by Peter I. Corke
%
% This file is part of The Machine Vision Toolbox for Matlab (MVTB).
%
% MVTB is free software: you can redistribute it and/or modify
% it under the terms of the GNU Lesser General Public License as published by
% the Free Software Foundation, either version 3 of the License, or
% (at your option) any later version.
%
% MVTB is distributed in the hope that it will be useful,
% but WITHOUT ANY WARRANTY; without even the implied warranty of
% MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
% GNU Lesser General Public License for more details.
%
% You should have received a copy of the GNU Leser General Public License
% along with MVTB. If not, see <http://www.gnu.org/licenses/>.
function Z = testpattern(type, w, varargin)
if length(w) == 1
z = zeros(w);
elseif length(w) == 2
z = zeros(w(2), w(1));
end
switch type,
case {'sinx'}
if nargin > 2,
ncycles = varargin{1};
else
ncycles = 1;
end
x = 0:(numcols(z)-1);
clength = numcols(z)/ncycles;
z = repmat( sin(x/(clength)*ncycles*2*pi), numrows(z), 1);
case {'siny'}
if nargin > 2
ncycles = varargin{1};
else
ncycles = 1;
end
clength = numrows(z)/ncycles;
y = [0:(numrows(z)-1)]';
z = repmat( sin(y/(clength)*ncycles*2*pi), 1, numrows(z));
case {'rampx'}
if nargin > 2
ncycles = varargin{1};
else
ncycles = 1;
end
clength = numcols(z)/ncycles;
x = 0:(numcols(z)-1);
z = repmat( mod(x, clength) / (clength-1), numrows(z), 1);
case {'rampy'}
if nargin > 2
ncycles = varargin{1};
else
ncycles = 1;
end
clength = numrows(z)/ncycles;
y = [0:(numrows(z)-1)]';
z = repmat( mod(y, clength) / (clength-1), 1, numcols(z));
case {'line'}
% args:
% angle intercept
nr = numrows(z);
nc = numcols(z);
c = varargin{2};
theta = varargin{1};
if abs(tan(theta)) < 1,
x = 1:nc;
y = round(x*tan(theta) + c);
s = find((y >= 1) & (y <= nr));
else
y = 1:nr;
x = round((y-c)/tan(theta));
s = find((x >= 1) & (x <= nc));
end
for k=s,
z(y(k),x(k)) = 1;
end
case {'squares'}
% args:
% pitch diam
nr = numrows(z);
nc = numcols(z);
d = varargin{2};
pitch = varargin{1};
if d > (pitch/2),
fprintf('warning: squares will overlap\n');
end
rad = floor(d/2);
d = 2*rad;
for r=pitch/2:pitch:(nr-pitch/2)
for c=pitch/2:pitch:(nc-pitch/2),
z(r-rad:r+rad,c-rad:c+rad) = ones(d+1);
end
end
case {'dots'}
% args:
% pitch diam
nr = numrows(z);
nc = numcols(z);
d = varargin{2};
pitch = varargin{1};
if d > (pitch/2)
fprintf('warning: dots will overlap\n');
end
rad = floor(d/2);
d = 2*rad;
s = kcircle(d/2);
for r=pitch/2:pitch:(nr-pitch/2),
for c=pitch/2:pitch:(nc-pitch/2),
z(r-rad:r+rad,c-rad:c+rad) = s;
end
end
otherwise
disp('Unknown pattern type')
im = [];
end
if nargout == 0
idisp(z);
else
Z = z;
end