bwconncomp returns a variable with 4 fields. one of them is pixelIdxlist. it contains the connected component list.how can we extract each component and show in different images.

in my code pixelIdx has 4 components:

 PixelIdxList: {[866x1 double]  [628x1 double]  [1092x1 double]  [4x1 double]}

how can I store each component in a different image so that it can b processed further..

can anyone plz help me to write the code for this..

[Iman Haghgooie]

Check out: http://www.mathworks.com/help/images/ref/labelmatrix.html

I ran into the same issue :)

Answer 1

[Anand]

You can use the regionprops function with 'Image' as the requested statistic and pass the output of bwconncomp to it. Your code would look like this:

BW = imread('text.png');
CC = bwconncomp(BW);

stats = regionprops(CC,'Image');

%Display the first component as an image
imshow(stats(1).Image);

Note that you can instead directly call regionprops on the binary image BW. regionprops will internally invoke bwconncomp for you.

stats = regionprops(BW,'Image');

Answer 2

[Image Analyst]

I know this is old, but if anyone wants to do this, each blob that was measured (4 in Gaur's case) will have a label if you called bwlabel() or bwconncomp() prior to calling regionprops(). To get each by itself, you use ismember():

[labeledImage, numberOfBlobs] = bwlabel(binaryImage);
measurements = regionprops(labeledImage);
for blob = 1 : numberOfBlobs
  thisBlob = ismember(labeledImage, 1);

    % Display blob in a new figure.
    figure;
    imshow(thisBlob); 

    % Or use imwrite if you want to save to disk.
    eightBitImage = uint8(255*(thisBlob>0));
    filename = sprintf('Blob #%d.png', blob);
    imwrite(eightBitImage, filename);
  end

You can also look at my Image Segmentation Tutorial to see how you can use the BoundingBox property if you want the blob cropped out to form a smaller image instead of the above, which has the full sized image.

[Iman Haghgooie]

Hi Image Analyst, bwlabel is the most common way of labeling connected pixels. But it is memory-intensive and computationally expensive. bwconncomp provides much better performance for real-time applications. Pls see below.