Write the function to return the x and y coordinates of the input pixel’s connected neighbours, i.e., the x and y coordinates of all pixels in the set c(p) for the given P.

I = imread('F:\IMAGE SYSTEMS\LAB 2\EEET2169-Lab2-main\images\iceberg.png');

J = double(I);

% Pixel of interest

poi = [190 180];

x0 = 190;

y0 = 180;

% n - neighbouring pixels

n1 = ([x0+1 y0]);

n2 = ([x0-1 y0]);

n3 = ([x0 y0+1]);

n4 = ([x0 y0-1]);

% v - intensity of the poi

vpoi = J(poi(1),poi(2));

v1 = J(n1(1),n1(2));

v2 = J(n2(1),n2(2));

v3 = J(n3(1),n3(2));

v4 = J(n4(1),n4(2));

% a - absolute value

a1 = abs(v1-vpoi);

a2 = abs(v2-vpoi);

a3 = abs(v3-vpoi);

a4 = abs(v4-vpoi);

I don't know how to proceed after this. Anyone please help me with this!

Answer 1

[Suraj Kumar]

Hi @RAHUL SURESHBABU,

You were on the right track to find the x and y coordinates of all connected neighbors of a specific pixel in an image. I've made a few enhancements to the script to improve its functionality:

1. I've introduced a threshold to determine when the intensity differences between the pixel of interest and its neighbors are small enough to consider them connected. This helps in accurately identifying connected pixels based on intensity similarity.

2. I've added boundary checks to ensure that the neighbor pixel indices are within the bounds of the image. This step is crucial for preventing errors when accessing pixel values, especially at the edges of the image.

You can refer to the attached code snippet below for a clearer understanding:

function connectedNeighbors = findConnectedNeighbors(imagePath, pixelCoords, threshold)
    I = imread(imagePath);
    J = double(I);    
    x0 = pixelCoords(1);
    y0 = pixelCoords(2);
    vpoi = J(x0, y0);
    neighbors = [
        x0+1, y0;
        x0-1, y0;
        x0, y0+1;
        x0, y0-1
    ];
    connectedNeighbors = [];
    for i = 1:size(neighbors, 1)
        xn = neighbors(i, 1);
        yn = neighbors(i, 2);
        if xn > 0 && xn <= size(J, 1) && yn > 0 && yn <= size(J, 2)
            vn = J(xn, yn);
            a = abs(vn - vpoi);
            if a <= threshold
                connectedNeighbors = [connectedNeighbors; xn, yn];
            end
        end
    end
end

Hope this works for you!