I read a 3d image in matlab and converts to a matrix of size 100036*3.Now i want to find correlation coefficient of this matrix separately in x,y &z direction in matlab

I want to find correlaion coefficient in different directions separately .But for finding correlation coefficient i need two variable.So how i can find correlation coefficients in x- direction, y-direction and z-direction separately

Answer 1

[Subhajyoti]

Hi Reet,

To efficiently compute the correlation coefficients, we will shift the data along each direction and compute the correlation between the original and shifted data.

Here’s MATLAB code snippet to illustrate using ‘corrcoef’ function for data-matrix:

Step 1: Read the 3D image

    % For demonstration, we will generate a random 3D matrix
    Nx = 100; Ny = 100; Nz = 10; % Replace with actual dimensions
    img3D = rand(Nx, Ny, Nz); % Replace with actual image data
    sizeOfImage = size(img3D)

sizeOfImage = 1x3

100 100 10

<mw-icon class=""></mw-icon>

<mw-icon class=""></mw-icon>

Step 2: Calculate correlation coefficients

    % For x-direction
    x_original = img3D(1:end-1, :, :);
    x_shifted = img3D(2:end, :, :);
    x_original_flat = x_original(:);
    x_shifted_flat = x_shifted(:);
    corr_x = corrcoef(x_original_flat, x_shifted_flat);
    corr_x = corr_x(1, 2) % Get the correlation coefficient

corr_x = 0.0035

    
    % For y-direction
    y_original = img3D(:, 1:end-1, :);
    y_shifted = img3D(:, 2:end, :);
    y_original_flat = y_original(:);
    y_shifted_flat = y_shifted(:);
    corr_y = corrcoef(y_original_flat, y_shifted_flat);
    corr_y = corr_y(1, 2)

corr_y = -0.0013

    
    % For z-direction
    z_original = img3D(:, :, 1:end-1);
    z_shifted = img3D(:, :, 2:end);
    z_original_flat = z_original(:);
    z_shifted_flat = z_shifted(:);
    corr_z = corrcoef(z_original_flat, z_shifted_flat);
    corr_z = corr_z(1, 2)

corr_z = 1.6429e-04

Step 3: Display the results

    fprintf('Correlation coefficient in x direction: %f\n', corr_x);

Correlation coefficient in x direction: 0.003540

    fprintf('Correlation coefficient in y direction: %f\n', corr_y);

Correlation coefficient in y direction: -0.001345

    fprintf('Correlation coefficient in z direction: %f\n', corr_z);

Correlation coefficient in z direction: 0.000164

For more details on the Correlation coefficients, go through the following MathWorks documentation.

https://www.mathworks.com/help/matlab/ref/corrcoef.html

[Harpreet]

Thanku you so much for your help subhajyoti