Error Creating ROI mask

Im trying to creake multiple binary masks from a bathc of pictures but when i try to use the create mask function when inside a bigger loop an error saying pops out

Error using images.roi.internal.mixin.CreateMask/validateInputs

createMask expects a current figure containing an image.

Error in images.roi.Freehand/createMask

Error in multiplesegmentation (line 34)

BW = createMask(mask);

Here its my code to note when doing this process one by one it doesnt has this problem

clc;

close all;

imtool close all;

clear;

srcFile=dir('C:...\*.jpg');

for i=1:length(srcFile)

filename=strcat('C:...\',srcFile(i).name);

img=imread(filename);

%figure,imshow(k);

path=strcat('C:...\save\',srcFile(i).name);

I=rgb2gray(img);

se = strel('disk',45);

backgroun = imopen(I,se);

I2 = I - backgroun;

I3 = imadjust(I2);

segmentedLabels = imsegkmeans(I3,3);

boneMask = segmentedLabels==3;

%imshowpair(im, boneMask);

boneMask1 = bwareafilt(boneMask, 2);

%imshowpair(im, boneMask);

%title('SEG1 ');

blocations = bwboundaries(boneMask1,'noholes');

%figure,imshow(img, []);

for ind = 1:numel(blocations)

% Convert to x,y order.

pos = blocations{ind};

pos = fliplr(pos);

% Create a freehand ROI.

mask=drawfreehand('Position', pos);

BW = createMask(mask);

morph= imopen(BW,se);

%imshow(morph);

end

B = imoverlay(img,morph);

%imwrite(B,path);

figure,imshow(B);

title('nail found ');

end

Answer 1

[Saffan]

Hi Cristhian,

The “createMask” function requires the current figure in MATLAB to contain the image on which the ROI is drawn. In the provided code, the error occurs because the function is being called within a loop where multiple ROIs are drawn. However, the image associated with each ROI is not present in the current figure, leading to the error.

To resolve this issue, we need to ensure that the image is displayed in the current figure before creating the masks. This can be achieved by creating a new figure for each image as shown in the following code snippet:

figure; % Create a new figure for each image 
imshow(img, []); 
hold on; 
for ind = 1:numel(blocations) 
    pos = blocations{ind}; 
    pos = fliplr(pos); 
    mask = drawfreehand('Position', pos); 
    BW = createMask(mask); 
    morph = imopen(BW, se); 
end 
hold off; 

Please refer to this for more information:

https://www.mathworks.com/help/releases/R2023a/images/ref/images.roi.assistedfreehand.createmask.html