IDE@L: post_hysteresis=canny_edges(im,min_hysteresis_thresh, max_hysteresis_thresh,sigma); - File Exchange

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T_edge=edge_parameter(imo) Edge detection parameter input
ait_imgneg(pic) % Function Developed by Fahd A. Abbasi.
edgelink(im, minlength, locat... EDGELINK - Link edge points in an image into lists
maxlinedev(x,y) MAXLINEDEV - Find max deviation from a line in an edge contour.
mergeseg(seglist, angtol, lin... MERGESEG - Line segment merging function.
post_hysteresis=canny_edges(i...
threshold=perimeter_parameter... Edge detection parameter input
xlswrite(m,header,colnames,fi... xlswrite Easily create an Excel spreadsheet from MATLAB
IDEAL_gui.m
Ring_Reconstruction.m
Ring_V.m
Ring_export.m
Ring_label2.m
loadfile.m
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from IDE@L by Joseph Morlier
IDE@L is a toolbox for Matlab dealing with Tree rings detection by image processing. This is a Graph
post_hysteresis=canny_edges(im,min_hysteresis_thresh, max_hysteresis_thresh,sigma);
 

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% CAP 5405, Fall 2005                                                                                     %

% Canny Edge Detector                                                                                   %

% Mikel Rodriguez                                                                                            %

%                                                                                                                       %

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function post_hysteresis=canny_edges(im,min_hysteresis_thresh, max_hysteresis_thresh,sigma);

%%INIT VARIABLES:

ORIGINAL_IMAGE=im;

%%Convert to double:

ORIGINAL_IMAGE=im2double(ORIGINAL_IMAGE);    

%%Save height and width

[H,W]=size(ORIGINAL_IMAGE);         

%%Derivatives in x and y

derivative_x=zeros(H,W);              

derivative_y=zeros(H,W);    

%%Gaussian kernel

size_of_kernel = 6*sigma+1;         

adjust= ceil(size_of_kernel/2)

Y_GAUSSIAN=zeros(size_of_kernel,size_of_kernel);

X_GAUSSIAN=zeros(size_of_kernel,size_of_kernel);

%%Create gaussian kernels for both x and y directions based on the sigma

%%that was given.

for i=1:size_of_kernel

    for iiii=1:size_of_kernel

        Y_GAUSSIAN(i,iiii) = -( (i-((size_of_kernel-1)/2)-1)/( 2* pi * sigma^3 ) ) * exp ( - ( (i-((size_of_kernel-1)/2)-1)^2 + (iiii-((size_of_kernel-1)/2)-1)^2 )/ (2*sigma^2) );

    end

end

for i=1:size_of_kernel

    for iiii=1:size_of_kernel

        X_GAUSSIAN(i,iiii) = -( (iiii-((size_of_kernel-1)/2)-1)/( 2* pi * sigma^3 ) ) * exp ( - ( (i-((size_of_kernel-1)/2)-1)^2 + (iiii-((size_of_kernel-1)/2)-1)^2 )/ (2*sigma^2) );

    end

end



GRADIENT =  zeros(H,W);       

non_max = zeros(H,W);     

post_hysteresis = zeros(H,W); 

%%Image Derivatives:

 
for r=1+ceil(size_of_kernel/2):H-ceil(size_of_kernel/2)  

    for c=1+ceil(size_of_kernel/2):W-ceil(size_of_kernel/2)  

        reference_row=  r-ceil(size_of_kernel/2); 

        reference_colum=  c-ceil(size_of_kernel/2); 

        for yyy=1:size_of_kernel  

            for yyy_col=1:size_of_kernel  

                derivative_x(r,c) = derivative_x(r,c) + ORIGINAL_IMAGE(reference_row+yyy-1, reference_colum+yyy_col-1)*X_GAUSSIAN(yyy,yyy_col);

            end

        end

    end

end

 
for r=1+ceil(size_of_kernel/2):H-ceil(size_of_kernel/2)  

    for c=1+ceil(size_of_kernel/2):W-ceil(size_of_kernel/2) 

        reference_row=  r-ceil(size_of_kernel/2); 

        reference_colum=  c-ceil(size_of_kernel/2); 

        for yyy=1:size_of_kernel  

            for yyy_col=1:size_of_kernel 

                derivative_y(r,c) = derivative_y(r,c) + ORIGINAL_IMAGE(reference_row+yyy-1, reference_colum+yyy_col-1)*Y_GAUSSIAN(yyy,yyy_col);

            end

        end

    end

end

 
%%Compute the gradient magnitufde based on derivatives in x and y:

for r=1+ceil(size_of_kernel/2):H-ceil(size_of_kernel/2)  

    for c=1+ceil(size_of_kernel/2):W-ceil(size_of_kernel/2)  

        GRADIENT(r,c) = sqrt (derivative_x(r,c)^2 + derivative_y(r,c)^2 );

    end

end

%%Perform Non maximum suppression:

non_max = GRADIENT;

for r=1+ceil(size_of_kernel/2):H-ceil(size_of_kernel/2) 

    for c=1+ceil(size_of_kernel/2):W-ceil(size_of_kernel/2)  

    %%quantize:

        if (derivative_x(r,c) == 0) tangent = 5;       

        else tangent = (derivative_y(r,c)/derivative_x(r,c));   

        end

        if (-0.4142<tangent & tangent<=0.4142)

            if(GRADIENT(r,c)<GRADIENT(r,c+1) | GRADIENT(r,c)<GRADIENT(r,c-1))

                non_max(r,c)=0;

            end

        end

        if (0.4142<tangent & tangent<=2.4142)

            if(GRADIENT(r,c)<GRADIENT(r-1,c+1) | GRADIENT(r,c)<GRADIENT(r+1,c-1))

                non_max(r,c)=0;

            end

        end

        if ( abs(tangent) >2.4142)

            if(GRADIENT(r,c)<GRADIENT(r-1,c) | GRADIENT(r,c)<GRADIENT(r+1,c))

                non_max(r,c)=0;

            end

        end

        if (-2.4142<tangent & tangent<= -0.4142)

            if(GRADIENT(r,c)<GRADIENT(r-1,c-1) | GRADIENT(r,c)<GRADIENT(r+1,c+1))

                non_max(r,c)=0;

            end

        end

    end

end

 
post_hysteresis = non_max;

 
for r=1+ceil(size_of_kernel/2):H-ceil(size_of_kernel/2)  

    for c=1+ceil(size_of_kernel/2):W-ceil(size_of_kernel/2)  

        if(post_hysteresis(r,c)>=max_hysteresis_thresh) post_hysteresis(r,c)=1;

        end

        if(post_hysteresis(r,c)<max_hysteresis_thresh & post_hysteresis(r,c)>=min_hysteresis_thresh) post_hysteresis(r,c)=2;

        end

        if(post_hysteresis(r,c)<min_hysteresis_thresh) post_hysteresis(r,c)=0;

        end 

    end

end

vvvv = 1; 

while (vvvv == 1)

    vvvv = 0;

    for r=1+ceil(size_of_kernel/2):H-ceil(size_of_kernel/2)  

        for c=1+ceil(size_of_kernel/2):W-ceil(size_of_kernel/2)  

            if (post_hysteresis(r,c)>0)      

                if(post_hysteresis(r,c)==2) 
            if( post_hysteresis(r-1,c-1)==1 | post_hysteresis(r-1,c)==1 | post_hysteresis(r-1,c+1)==1 | post_hysteresis(r,c-1)==1 |  post_hysteresis(r,c+1)==1 | post_hysteresis(r+1,c-1)==1 | post_hysteresis(r+1,c)==1 | post_hysteresis(r+1,c+1)==1 ) post_hysteresis(r,c)=1;

                        vvvv == 1;

                    end

                end

            end

        end

    end

end

 
for r=1+ceil(size_of_kernel/2):H-ceil(size_of_kernel/2) 

    for c=1+ceil(size_of_kernel/2):W-ceil(size_of_kernel/2)  

        if(post_hysteresis(r,c)==2) 

            post_hysteresis(r,c)==0;

        end   

    end

end

%%Image Derivatives:

for r=1+ceil(size_of_kernel/2):H-ceil(size_of_kernel/2)  

    for c=1+ceil(size_of_kernel/2):W-ceil(size_of_kernel/2)  

        reference_row=  r-ceil(size_of_kernel/2); 

        reference_colum=  c-ceil(size_of_kernel/2); 

        for yyy=1:size_of_kernel  

            for yyy_col=1:size_of_kernel  

                derivative_x(r,c) = derivative_x(r,c) + ORIGINAL_IMAGE(reference_row+yyy-1, reference_colum+yyy_col-1)*X_GAUSSIAN(yyy,yyy_col);

            end

        end

    end

end

 
for r=1+ceil(size_of_kernel/2):H-ceil(size_of_kernel/2)  

    for c=1+ceil(size_of_kernel/2):W-ceil(size_of_kernel/2) 

        reference_row=  r-ceil(size_of_kernel/2); 

        reference_colum=  c-ceil(size_of_kernel/2); 

        for yyy=1:size_of_kernel  

            for yyy_col=1:size_of_kernel 

                derivative_y(r,c) = derivative_y(r,c) + ORIGINAL_IMAGE(reference_row+yyy-1, reference_colum+yyy_col-1)*Y_GAUSSIAN(yyy,yyy_col);

            end

        end

    end

end

 
%%Compute the gradient magnitufde based on derivatives in x and y:

 

for r=1+ceil(size_of_kernel/2):H-ceil(size_of_kernel/2)  

    for c=1+ceil(size_of_kernel/2):W-ceil(size_of_kernel/2)  

        GRADIENT(r,c) = sqrt (derivative_x(r,c)^2 + derivative_y(r,c)^2 );

    end

end

 
%%Perform Non maximum suppression:

 

non_max = GRADIENT;

for r=1+ceil(size_of_kernel/2):H-ceil(size_of_kernel/2) 

    for c=1+ceil(size_of_kernel/2):W-ceil(size_of_kernel/2)  

       

        %%quantize:

        if (derivative_x(r,c) == 0) tangent = 5;       

        else tangent = (derivative_y(r,c)/derivative_x(r,c));   

        end

        if (-0.4142<tangent & tangent<=0.4142)

            if(GRADIENT(r,c)<GRADIENT(r,c+1) | GRADIENT(r,c)<GRADIENT(r,c-1))

                non_max(r,c)=0;

            end

        end

        if (0.4142<tangent & tangent<=2.4142)

            if(GRADIENT(r,c)<GRADIENT(r-1,c+1) | GRADIENT(r,c)<GRADIENT(r+1,c-1))

                non_max(r,c)=0;

            end

        end

        if ( abs(tangent) >2.4142)

            if(GRADIENT(r,c)<GRADIENT(r-1,c) | GRADIENT(r,c)<GRADIENT(r+1,c))

                non_max(r,c)=0;

            end

        end

        if (-2.4142<tangent & tangent<= -0.4142)

            if(GRADIENT(r,c)<GRADIENT(r-1,c-1) | GRADIENT(r,c)<GRADIENT(r+1,c+1))

                non_max(r,c)=0;

            end

        end

    end

end

 
post_hysteresis = non_max;

 
for r=1+ceil(size_of_kernel/2):H-ceil(size_of_kernel/2)  

    for c=1+ceil(size_of_kernel/2):W-ceil(size_of_kernel/2)  

        if(post_hysteresis(r,c)>=max_hysteresis_thresh) post_hysteresis(r,c)=1;

        end

        if(post_hysteresis(r,c)<max_hysteresis_thresh & post_hysteresis(r,c)>=min_hysteresis_thresh) post_hysteresis(r,c)=2;

        end

        if(post_hysteresis(r,c)<min_hysteresis_thresh) post_hysteresis(r,c)=0;

        end 

    end

end


 

vvvv = 1; 

 

while (vvvv == 1)

   

    vvvv = 0;

   

    for r=1+ceil(size_of_kernel/2):H-ceil(size_of_kernel/2)  

        for c=1+ceil(size_of_kernel/2):W-ceil(size_of_kernel/2)  

            if (post_hysteresis(r,c)>0)      

                if(post_hysteresis(r,c)==2) 

                   

                   

                    if( post_hysteresis(r-1,c-1)==1 | post_hysteresis(r-1,c)==1 | post_hysteresis(r-1,c+1)==1 | post_hysteresis(r,c-1)==1 |  post_hysteresis(r,c+1)==1 | post_hysteresis(r+1,c-1)==1 | post_hysteresis(r+1,c)==1 | post_hysteresis(r+1,c+1)==1 ) post_hysteresis(r,c)=1;

                        vvvv == 1;

                    end

                end

            end

        end

    end

   

end

 

 

 

for r=1+ceil(size_of_kernel/2):H-ceil(size_of_kernel/2) 

    for c=1+ceil(size_of_kernel/2):W-ceil(size_of_kernel/2)  

        if(post_hysteresis(r,c)==2) 

            post_hysteresis(r,c)==0;

        end   

    end

end
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