Trace boundaries of objects in NOT binary images

Hello,

I'd need some help. I need to trace region boundaries in an image. I would need exactly what bwboundaries does but in multi-label images because my image is not binary.

I have a lot of objects, holes, objects inside other objects ... I have to detect all the objects and get its boundaries. I have found only bwboundaries but i couln't find anything for not binary images.

Thank you very much

Answer 1

[Image Analyst]

You can binarize the image and then call it

binaryImage = labeledImage > 0

If the objects are touching and still labeled (which you must have done with a custom algorithm) then you will need multiple binary images:

binaryImage = labeledImage == labelNumberThatYouWant;

do it for every label number that you want the boundary of.

[Silvia]

If I understand I would have a binary image for each object. I mean, if I have 5 objects (labeled from 1 to 5) I would have 5 binary images and I would run bwboundaries for each one.

Ok! I thougth that maybe exist a function similar to bwboundaries but for this kind of images.

Thanks

[Image Analyst]

Most likely you do not need to do that because in nearly all situations, the labels don't touch. Perhaps you're thinking of a classified image instead of a labeled image. In situations with normal labeled image (not a classified image), in 99.9% of the cases you'd have just one single binary image like I showed first.

See this example

0 0 1 0 2
0 1 1 0 2  Normal, labeled image.
0 1 1 0 2

0 0 1 2 2
0 1 1 2 2  Classified image, or highly unusual, labeled image.
0 1 1 0 2

[Ankit Sahay]

Hi Image Analyst! I have come across a similar problem, which is a "Classified image" according to your comment above. Can you advise me on how to deal with such a situation? For example, in the matrix corresponding to the above "Classified image", I would like to have 4 labels.

Please let me know if I need to ask this as a new question, since this question is 7 years old. Thanks!

[Image Analyst]

I have no idea what you want - no idea what "deal with" means to you. Start a new question and attach your image(s).

[Ankit Sahay]

Okay. Thanks!