Selecting multiple ROI in images for processing

Question

Vivek 2022-8-9

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https://ww2.mathworks.cn/matlabcentral/answers/1776130-selecting-multiple-roi-in-images-for-processing

回答： Image Analyst 2022-12-7

I would like to select multiple rectangular regions in an image and would like to plot the selected 2D region's as 1D plots.How can I do this in matlab. Also is there a easy way to use the same ROI on multiple images.

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DGM 2022-8-9

编辑：DGM 2022-8-9

When you say you want to plot the regions as a 1D plot, are you trying to plot the intensity profile along the polyline that defines the border of the ROI?

If so, do the images all share the same geometry?

萌萌 2022-8-9

hello,

How can we use matlab to transform an image into short lines in the length of micrometers,

all short lines will represent the grayscale, or maybe the lightness of the image,

after we get the short lines file, we will use it for etching out textures.

Thank you.

Mikko

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Answer 1

Image Analyst 2022-8-9

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编辑：Image Analyst 2022-8-9

See attached demos.

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DGM 2022-12-7

编辑：DGM 2022-12-7

Note that drawpoint(), drawpolygon(), etc all require Image Processing Toolbox. Otherwise, if you have IPT, but are running something older than R2018b, there may be other options. If that's the case, you'll have to describe your needs.

Muhammad Mubeen Tariq 2022-12-7

编辑：Muhammad Mubeen Tariq 2022-12-7

@Image Analyst Hello Sir! Thank you so much for replying. Basically, there is picture of bubble sheet (like used in exams) which contains about 10 to 20 MCQs based bubble options. Each option has 4 bubbles, one bubble filled and other 3 are empty. I need any method or code by which i can pick only filled bubbles from picture because i have to apply ink mismatch on those bubbles to detect ink forgery. If i use your codes provided above, i have to manually select those filled bubbles and it would be very difficult to select ROI on 10 to 20 bubbles. Please can you help me little bit, i would be very thankful to you. If you have any mail or social media where i can contact you and could explain the whole scenario in detail. Hoping for positive response.

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Answer 2

yanqi liu 2022-8-9

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https://ww2.mathworks.cn/matlabcentral/answers/1776130-selecting-multiple-roi-in-images-for-processing#answer_1023355

在 MATLAB Online 中打开

yes，sir，may be use roipoly to make shape，such as

im = imread('cameraman.tif');
figure; imshow(im); hold on;
pts = [];
while 1
    [bw,xi,yi] = roipoly(im);
    hold on;
    pts{end+1} = [xi(:) yi(:)];
    plot(xi(:), yi(:), 'r-');
    tm = [];
    for i = 1 : length(xi)-1
        tm=[tm; xi(i) yi(i) xi(i+1) yi(i+1)];
    end
    im=insertShape(im,'Line',tm,'Color','r','LineWidth',1);
    choice = questdlg('break?', ...
        'break', ...
        'Yes','No','No');
    switch choice
        case 'Yes'
            break;
        case 'No'
            continue;
    end
end