ELDERZUCKEREDGE - Multi-scale edge detector.

Contents

Description

This function runs the Elder and Zucker multi-scale edge detector of [EZ98] and returns the edgel image.

Syntax

   edgemap = ELDERZUCKEREDGE(I);
   [edgemap,scmap,blur] = ELDERZUCKEREDGE(I, sigma);

Inputs

I : input image.

sigma : an estimate of the sensor noise of the image.

Outputs

edgemap : an edge map, not necessarily optimized.

scmap : optional output storing the minimum reliable scale of the second derivative estimator.

blur : optional output storing the blur estimate at every pixel.

References

[EZ98] J.H. Elder and S.W. Zucker: "Local scale control for edge detection and blur estimation", IEEE Trans. on Pattern Analysis and Machine Intelligence, 20(7), 1998. http://ieeexplore.ieee.org/xpls/abs_all.jsp?arnumber=689301&tag=1

[Elder99] J.H. Elder: "Are edges incomplete?", International Journal of Computer Vision, 1999. http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.27.9846

See also

Ressembles: EDGECORNER, CANNYEDGE, CANNYEDGEPROD, CANNYEDGEMAP, SDGDEDGE, CONGRUENCYEDGE, COMPASSEDGE, ANISOEDGE, ROTHWELLEDGE, KOETHEDGE, PETROUEDGE. Requires: ELDERZUCKEREDGE_BASE.

Function implementation

function [edgemap, varargout] = elderzuckeredge(I, varargin)

parsing parameters

error(nargchk(1, 12, nargin, 'struct'));
error(nargoutchk(1, 3, nargout, 'struct'));

if ~isnumeric(I)
    error('elderzuckeredge:inputparameter','a matrix is required in input');
end

p = createParser('ELDERZUCKEREDGE');
p.addOptional('sigma', 0.05, @(x)isscalar(x) && x>=0.05);
p.addParamValue('reduce', false, @(x)islogical(x) || ...
    (ischar(x) && any(strcmpi(x,{'igray','imax','isum','gmax','eor'}))));
% parse and validate all input arguments
p.parse(varargin{:});
p = getvarParser(p);

main calculation

if nargout==1
    edgemap = elderzuckeredge_base(I, p.sigma, p.reduce);

else
    [edgemap, scmap, blur] = elderzuckeredge_base(I, p.sigma, p.reduce);
    if nargout>=2,     varargout{1} = scmap;     end
    if nargout==3,     varargout{2} = blur;     end
end

display

if p.disp
    figure, imagesc(edgemap), axis image off, title('EZ edge map');
    if size(edgemap,3) == 1, colormap 'gray'; end;
    if nargout==3
        figure, subplot(1,2,1)
        imshow(scmap), axis image off, title('minimum reliable scale');
        subplot(1,2,2)
        imshow(rescale(blur)), axis image off, title('blur estimate');
    end
end

end % end of elderzuckeredge