How to interpret the wrong image background of data augmentation?

I'm working in semantic segmentation and faced a problem with the output of data augmentation after running the attached code. This problem is related to the background of some ground truth images; instead of a black background, it displays white, as shown in the attached screenshot.

    for j = 1:numImages
        % Read the original image and ground truth
        img = readimage(imdsClass, j);
        gtImg = readimage(gtImdsClass, j);
        gtImg=imcomplement(gtImg);
        % Generate filenames for the original images
        originalImgName = fullfile(classImageFolder, ['original_' num2str(j) '_' classLabel '.jpg']);
        originalGtImgName = fullfile(classGTFolder, ['original_' num2str(j) '_' classLabel '.png']);
        
        % Save the original image and ground truth
        imwrite(img, originalImgName);
        imwrite(gtImg, originalGtImgName);
    end
    
    % Perform augmentation for the images that need to be generated
    for j = 1:numToGenerate
        % Read an image and its corresponding ground truth
        img = readimage(imdsClass, mod(j, numImages) + 1);
        gtImg = readimage(gtImdsClass, mod(j, numImages) + 1);
        gtImg=imcomplement(gtImg);
        % Apply augmentation (random rotation and flipping)
        x = randi([-30, 30], 1);  % Random rotation angle
        y = randi([1, 2], 1);     % Random flip direction (1: vertical, 2: horizontal)
        
        % Augment the image and ground truth
        augmentedImg = imrotate(img, x, 'bilinear', 'crop');
        augmentedImg = flip(augmentedImg, y);
        
        augmentedGtImg = imrotate(gtImg, x, 'nearest', 'crop');
        augmentedGtImg = flip(augmentedGtImg, y);
        
        % Generate filenames for the augmented images
        augmentedImgName = fullfile(classImageFolder, ['augmented_' num2str(j) '_' classLabel '.jpg']);
        augmentedGtImgName = fullfile(classGTFolder, ['augmented_' num2str(j) '_' classLabel '.png']);
        
        % Save the augmented image and ground truth
        imwrite(augmentedImg, augmentedImgName);
        imwrite(augmentedGtImg, augmentedGtImgName);
    end

[Shivansh]

Hi Abdulrahman,

I tried to reproduce the issue but the code works fine on my end.

Please share a few images for reproducing the issue.

[Abdulrahman]

Hi Shivansh

This atteached file is the data that I used.

Answer 1

[Image Analyst]

Why are you calling imcomplement? Try not doing that.

What is the original background: white or black?

Finally, you could just check if it's white in the upper left pixel, and invert it if it's white.

if augmentedImg(1,1) ~= 0
    augmentedImg = ~augmentedImg; % or imcomplement(augmentedImg), whatever works.
end

[Abdulrahman]

Dear Image Analyst

The original background images is black.

My problem is how to unifirm the background of all data as shown in attached pic.

I run the code without gtImg=imcomplement(gtImg);for small data (attached DA) and got correct results using your code (if augmentedImg(1,1) ~= 0 ......) but I got wrong results for whole dataset.

[Image Analyst]

Why are you manually augmenting your images instead of using augment?