How to create binary image mask if my data image have multiple lesion in 1 image?

My question is, how can I create binary mask if my image data have multiple lesion in 1 image?

Below I shared examole of my single lesion (already in binary mask);

According to the codes I wrote, it is drawn by free hand.

Below I shared my multiple lesion image data:

Answer 1

[Milan Bansal]

Hi Dayangku Nur Faizah Pengiran Mohamad

I understand that you wish to select multiple lesions in a single image using drawfreehand and save the final mask as binary image. You might also want to save a binary mask for individual lesions.

Please refer to the following steps to achieve this.

1. Manual Lesion Selection: Each time you use drawfreehand, you manually outline a lesion in the image.
2. Binary Mask Creation: The binary mask for the lesion is created with createMask.
3. Saving Individual Lesions: Each lesion is saved as a separate binary image.
4. Combining Masks: The current lesion mask is added to a final combined mask using a logical OR (|), allowing for multiple lesion regions to be merged.
5. Stopping Condition: After drawing a lesion, you are prompted whether to continue or stop. If you enter 'n', the loop breaks, and the process stops.

Please refer to following code snippet for implementation:

% Read the image
img = imread('lp.png');
% Display the image
imshow(img);
hold on;  % Hold on to allow multiple drawings
% Initialize the combined mask
[rows, cols, ~] = size(img);
combinedMask = false(rows, cols); % Binary mask initialized to all false

% Loop to allow manual drawing of multiple lesions
while true
    % Manually select a lesion using drawfreehand
    h = drawfreehand('Color', 'r');
    
    % Create binary mask for the selected lesion
    lesionMask = createMask(h);
    
    % Save the individual lesion mask as a binary image
    % Remove this step if you do not wish to save mask for each lesion.
    imwrite(lesionMask, ['lesion_' num2str(lesionCount) '.png']);
    
    % Add the current lesion mask to the combined mask
    combinedMask = combinedMask | lesionMask;
    
    % Ask user if they want to select another lesion
    cont = input('Do you want to select another lesion? (y/n): ', 's');
    if strcmpi(cont, 'n')
        break;  % Exit the loop if no more lesions to draw
    end
end
% Display the final combined mask
figure;
imshow(combinedMask);
title('Final Combined Mask for All Lesions');
% Optionally, save the combined mask
imwrite(combinedMask, 'combined_lesion_mask.png');

Please refer to the following documentation to learn more:

• drawfreehand: https://www.mathworks.com/help/images/ref/drawfreehand.html
• createMask: https://www.mathworks.com/help/images/ref/imroi.createmask.html

Hope this helps!