How to interpret the wrong image background of data augmentation?

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Abdulrahman
Abdulrahman 2024-9-8
编辑： Image Analyst 2024-9-9
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
  2 个评论
Shivansh
Shivansh 2024-9-8
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.

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回答（1 个）

Image Analyst
Image Analyst 2024-9-8
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
  2 个评论
Abdulrahman
Abdulrahman 2024-9-8
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.

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