how to connect edges to nodes in a image using minimum spanning tree approach

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Raghu Rao
Raghu Rao 2017-4-6
回答： Jaynik 2024-10-30，7:12
I am doing my project on graph matching in hand written image, i want to represent a given word image in graph, am using the below algorithm.
input image
output of my code
expected output in this form
Algorithm:
input: Binary image B, Grid width w, Grid height h
Output: Graph g = (V, E) with nodes V and edges E
1: function Grid(B,w,h)
2: for i ← 1 to number of columns C = Width of B/w do
3: for j ← 1 to number of rows R = Height of B/h do
4: V = V ∪ {(xm, ym) | (xm, ym) is the centre of mass of segment sij}
5: for Each pair of nodes (u, v) ∈ V × V do
6: E = E ∪ (u, v) if associated segments are connected by NNA, MST, or DEL
7: return g
am already find the center of mass using this am plotting the points after plotting the points i do not know how to add the edges to using minimum spanning tree approch
this my code
clc;
clear all;
close all;
X=imread('i2.jpg');
imfinfo('i2.jpg')
figure,imshow(X)
b = imresize(X,[100,100]);
si = size(b,1);
sj = size(b,2);
figure;imshow(b);
% Binarization
th = graythresh(b);
I = im2bw(b,th);
w = 10;
h = 10;
c=si/w;
r=sj/h;
kl=bwmorph(~I,'thin',inf);
figure,imshow(kl)
R(:,:)=kl(:,:);
I=1;
U1=w;
J=1;
U2=h;
E=1;
for i=1:r
for j=1:c
B(I:U1,J:U2)=R(I:U1,J:U2);
[x,y]=find(B==1);
CX=mean(x);
CY=mean(y);
CXX(E)=CX
CYY(E)=CY
T(I:U1,J:U2)=B(I:U1,J:U2);
J=J+w;
U2=U2+h;
E=E+1;
clear B x y
end
I=I+w;
U1=U1+h;
J=1;
U2=h;
end
imshow(R)
hold on
hold on
plot(CYY,CXX,'.c')
hold off
am plotting using the CXX and CYY values i do not know how to add the edges to plotted points using minimum spanning tree approach. Please give me some code it will help me to complete my project

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回答（1 个）

Jaynik
Jaynik 2024-10-30，7:12
Hi Raghu,
MATLAB's built-in functions can be used to compute and plot the MST based on the coordinates of the centers of mass already calculated. These steps can be followed:
  1. Calculate Pairwise Distances: Use the Euclidean distance between each pair of nodes (centers of mass).
  2. Construct the MST: Use the graph and minspantree functions to construct the MST.
You can use the following code after obtaining the CXX and CYY values:
numPoints = length(CXX);
distances = zeros(numPoints);
for i = 1:numPoints
for j = 1:numPoints
distances(i, j) = sqrt((CXX(i) - CXX(j))^2 + (CYY(i) - CYY(j))^2);
end
end
% Construct the graph
G = graph(distances);
% Compute the minimum spanning tree
T = minspantree(G);
% Plot the MST
figure;
plot(CYY, CXX, 'o'); % Plot points
hold on;
[x, y] = find(T.Edges.EndNodes);
for i = 1:length(x)
plot([CYY(x(i)), CYY(y(i))], [CXX(x(i)), CXX(y(i))], '-r');
end
hold off;
You can refer to the following documentation to read more about these functions:
Hope this helps!

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