save only specefic connected components

Hi, From a gray image , I extract all the connected components using bwconcomp, Then I work on each connected component. I want to draw in a new image with the size of the originam image some specefic connected components. I saw many works based on the area , the biggest component ... but for me I have new parameter that will filter the cinnected components, How can I draw in a new image with the original image size a specific connected component in its original place?? Thank you :)

Answer 1

[Image Analyst]

You can extract any component from your labeled image into a new binary image using ismember:

binaryImage = ismember(labeledImage, index);

This will get only one blob - the one that was labeled with a number of "index".

If you want to mask the image with that blob and get a gray scale image then do this:

maskedImage = grayImage; % Initialize
maskedImage(~binaryImage) = 0; % Do the masking.

[Flore Massoulié]

thank you for your reply, sorry but I will add many components in the same image, how can I save their indexes ? I didn't get the idea :(

[Flore Massoulié]

for example like this,

[Image Analyst]

index can be an array of indexes if you want to extract several components.

[Flore Massoulié]

Sorry but this is not working for me, my original image is Img and the component I want to draw exp F(i).Image, then when I do binaryImage = ismember(Img, F(i).Image); is that what you mean ? but I got a white image nothing in it

[Image Analyst]

Is "F(i).Image" a scalar integer that contains the ID label of the blob you want to extract? If so, then yes, that should work.

[Flore Massoulié]

Hi again, No F(i).Image is the image of the connected component;

[Image Analyst]

Since you already have the image of the connected component, you can just use it as a mask on the original image:

If you want to mask the image with that blob and get a gray scale image then do this:

maskedImage = grayImage; % Initialize
mask = F(i).Image > 0; % Convert "the image of the connected component" into a logical mask.
maskedImage(~mask) = 0; % Do the masking.