Introducing a border/outline to objects in an image.

Hi everyone,

I have a question about how to introduce an outline to a mask. Please check the original source image at: http://i39.tinypic.com/ap78s9.jpg. I would like the borders of the various objects in the mask to be outlined and each object identified as shown in: http://i39.tinypic.com/e839yt.jpg, both with an outline and an index number (so that the index number could be used to identify, and cross-refer the results generated by regionprops). This specific example was generated using ImageJ.

Any help would be much appreciated.

Thanks and have a good weekend.

Answer 1

[Chandra Kurniawan]

Irgb = imread('ap78s9.jpg');
Igray = rgb2gray(Irgb);
Ibw = im2bw(Igray,graythresh(Igray));
Ifill = imfill(Ibw,'holes');
B = bwboundaries(Ifill);
stat = regionprops(Ifill,'Centroid');

imshow(~Ibw); hold on
for k = 1 : length(B)
    b = B{k};
    c = stat(k).Centroid;
    plot(b(:,2),b(:,1),'g','linewidth',2);
    text(c(1),c(2),num2str(k),'backgroundcolor','g');
end

Answer 2

[Sean de Wolski]

I would guess one of these will be your friend:

doc bwperim
doc bwboundaries
doc bwtraceboundary