Using Linear indicies to create new image

Question

Theodore 2023-11-30

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2054379-using-linear-indicies-to-create-new-image

评论： DGM 2023-12-1

So i have an image that I have used region props to find the pixels that are contained in certain objects.

With this function I have the linear indecies for each pixel. I want to use these indicies to create a new binary image that is the same size as the original with true (Intensity=1) pixels for each of the linear index that correlated to the computed object.

Hopefully this makes sense. I am sure there is a simple solution that would solve this but as of right now I can't figure out what that is.

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Mathieu NOE 2023-11-30

it would certainly be more efficient if you could share your code

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Answer 1

Image Analyst 2023-11-30

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https://ww2.mathworks.cn/matlabcentral/answers/2054379-using-linear-indicies-to-create-new-image#answer_1363339

在 MATLAB Online 中打开

You need to label your binary image and then use ismember to extract out just certain ID(s) to a new binary image. For example

labeledImage = bwlabel(mask);
% Extract out blobs #3 and 8 to a new binary image:
mask2 = ismember(labeledImage, [3, 8]);

See my Image Segmentation Tutorial in my File Exchange for a full demo.

Image Analyst's File Exchange

It's a generic, general purpose demo of how to threshold an image to find blobs, and then measure things about the blobs, and extract certain blobs based on their areas or diameters.

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DGM 2023-12-1

在 MATLAB Online 中打开

blobs.png

Or to just get all the masks at once

% a mask with 5 blobs

inpict = imread('blobs.png');

mask = im2gray(inpict)>64;

imshow(mask,'border','tight')

% create label image

[labeledImage nblobs] = bwlabel(mask);

% a complete set of masks as a 4D stack

maskstack = labeledImage == reshape(1:nblobs,1,1,1,[]);

% show the mask stack using montage

montage(maskstack,'bordersize',3,'backgroundcolor',[0.2 1 0.8])

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Answer 2

Matt J 2023-11-30

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2054379-using-linear-indicies-to-create-new-image#answer_1363349

在 MATLAB Online 中打开

stats=regionprops(BW,'PixelIdxList');
Z0=false(size(BW));
for i=1:numel(stats)
    
    Z=Z0;
    Z(stats(i).PixelIdxList)=1;
    
    stats(i).BW=Z;  %isolated BW images of each region
    
end