My image is stored in struct format after loading a .mat image. How to convert it back into image form ? It load as a struct 1x1 format.

I want to load .mat images from a folder and display it as an image.

After loading a .mat image using load function,. How to convert it back into image form ? It loads as a struct 1x1 format.

Please Help me.

clc;
clear all;
close all;
warning off;

%%%%%%%%%%%%%%%%%% FEATURE MATCHING USING HAMMING DISTANCE %%%%%%%%%%%
input_features = getFeatures("F:\8th SEM\Dataset\CASIA\file6.jpg");%Complex image
subplot(1,2,1);imshow(input_features);title("Input Unknown Image");
input_features = double(input_features);

% List all images in the folder
folderPath = "F:\8th SEM\Extracted Features";
imageFiles = dir(fullfile(folderPath, '*.mat')); % Assuming images are in jpg format

% Initialize variables to store minimum distance and closest image
minDistance = Inf;
closestImage = '';
k=0;
minData=0;


% Loop through each image in the folder
for i = 1:length(imageFiles)
    
    % Load the image
    img_variable = imageFiles(i).name;
    currentFile = fullfile(folderPath, imageFiles(i).name);
    data=load(currentFile);
    data= struct2cell(data);
    extracted_features = double(data);
    
    % Calculate Hamming distance between target image and current image
    % Make sure both images have the same size
    difference =abs(input_features - extracted_features);
    distance = (sum(difference(:)));
    disp(distance);
    % Update closest image if distance is smaller than current minimum
    if distance < minDistance
        minDistance = distance;
        closestImage = imageFiles(i).name;
        minData=extracted_features;
        k=i;
    end
    
end


if minDistance > 5
    msgbox('Match NOT Found', 'Result', 'modal');
    disp(['Hamming distance: ', num2str((minDistance))]);
    
else 
    % Display closest image and its Hamming distance
    msgbox('Match Found', 'Result', 'modal');
    disp(['Closest image: ', imageFiles(k).name]);
    disp(['Hamming distance: ', num2str((minDistance))]);
    subplot(1,2,2);imshow(minData);title("Matched with:");
end

The error i am getting is:

Error using double

Conversion to double from cell is not possible.

Error in testUnknownImage (line 30)

extracted_features = double(data);

[DGM]

It's a hard to say without knowing what's in the .mat files.

[Ridhima Chopra]

It's an image consisting of complex values.

Answer 1

[Walter Roberson]

    data=load(currentFile);

The result of load() of a .mat file is a struct with one field for each variable loaded.

    data= struct2cell(data);

You convert the struct to a cell... okay, that is valid. The cell will have one entry for each variable that was loaded.

    extracted_features = double(data);

You cannot double() a cell. You can double(data{1}) ...

[Ridhima Chopra]

What does data{1} mean here?

[Voss]

data{1} is the contents of the first cell of the cell array data.

For example:

% data is a cell array with 5 elements (cells), each containing something different
data = {[1 2; 3 4], [5 6], [7; 8], [], 10}

data = 1×5 cell array
    {2×2 double}    {[5 6]}    {2×1 double}    {0×0 double}    {[10]}

% the contents of the first cell of data is a 2x2 matrix of doubles
data{1}

ans = 2×2

1 2 3 4

[Walter Roberson]

data{1} means the content of the first cell entry in the cell array data

In context, it would mean the content of the "first" variable loaded from the .mat file.

[Ridhima Chopra]

Thank you so much!! This really works!