which output is the segmented image?

    function wateralgo(img)

F=imread();

F=im2double(F);

%Converting RGB image to Intensity Image
r=F(:,:,1);
g=F(:,:,2);
b=F(:,:,3);
I=(r+g+b)/3;
imshow(I);

%Applying Gradient
hy = fspecial('sobel');
hx = hy';
Iy = imfilter(double(I), hy, 'replicate');
Ix = imfilter(double(I), hx, 'replicate');
gradmag = sqrt(Ix.^2 + Iy.^2);
figure, imshow(gradmag,[]), title('Gradient magnitude (gradmag)');

L = watershed(gradmag);
Lrgb = label2rgb(L);
figure, imshow(Lrgb), title('Watershed transform of gradient magnitude (Lrgb)');

se = strel('disk',20);
Io = imopen(I, se);
figure, imshow(Io), title('Opening (Io)');
Ie = imerode(I, se);
Iobr = imreconstruct(Ie, I);
figure, imshow(Iobr), title('Opening-by-reconstruction (Iobr)');

Ioc = imclose(Io, se);
figure, imshow(Ioc), title('Opening-closing (Ioc)');

Iobrd = imdilate(Iobr, se);
Iobrcbr = imreconstruct(imcomplement(Iobrd), imcomplement(Iobr));
Iobrcbr = imcomplement(Iobrcbr);
figure, imshow(Iobrcbr), title('Opening-closing by reconstruction (Iobrcbr)');

fgm = imregionalmin(Iobrcbr);
figure, imshow(fgm), title('Regional maxima of opening-closing by reconstruction (fgm)');

I2 = I;
I2(fgm) = 255;
figure, imshow(I2), title('Regional maxima superimposed on original image (I2)');

se2 = strel(ones(7,7));
fgm2 = imclose(fgm, se2);
fgm3 = imerode(fgm2, se2);
fgm4 = bwareaopen(fgm3, 20);
I3 = I;
I3(fgm4) = 255;
figure, imshow(I3), title('Modified regional maxima superimposed on original image (fgm4)');

bw = im2bw(Iobrcbr, graythresh(Iobrcbr));
figure, imshow(bw), title('Thresholded opening-closing by reconstruction (bw)');

D = bwdist(bw);
DL = watershed(D);
bgm = DL == 0;
figure, imshow(bgm), title('Watershed ridge lines (bgm)');

gradmag2 = imimposemin(gradmag, bgm | fgm4);
L = watershed(gradmag2);
I4 = I;
I4(imdilate(L == 0, ones(3, 3)) | bgm | fgm4) = 255;
figure, imshow(I4), title('Markers and object boundaries superimposed on original image (I4)');

Lrgb = label2rgb(L, 'jet', 'w', 'shuffle');
figure, imshow(Lrgb), title('Colored watershed label matrix (Lrgb)');

figure, imshow(I), hold on
himage = imshow(Lrgb);
set(himage, 'AlphaData', 0.3);
title('Lrgb superimposed transparently on original image');

the segmented image output should be taken to find out the shape features so i need to known which output to be taken....

[Walter Roberson]

Which variable did you store the segmented image into when you wrote the code?

Answer 1

[Image Analyst]

It looks like Marker controlled watershed segmentation as explained on this page: http://www.mathworks.com/help/images/examples/marker-controlled-watershed-segmentation.html

The variable L holds the segmented image. Each blob has it's own ID number in that image.

[Gowsalya Arumugam]

Thank you for your reply....my aim is to segment the below image

why do i need to segment this image before calculating the shape features...if i use the codes of Marker controlled watershed segmentation for the segmentation process which output should be taken to calculate the shape features like area,centroid,perimeter etc...

[Walter Roberson]

You do not need to segment the image before calculating the shape features. On the other hand, segmenting the image is one of the techniques that can be used to make it much easier to calculate the shape features.

[Image Analyst]

This is probably too challenging a project for you. If you still want to attempt it, then I suggest you follow some of the algorithms here: http://iris.usc.edu/Vision-Notes/bibliography/contentscartog.html#Cartography,%20Aerial%20Images,%20Remote%20Sensing,%20Buildings,%20Roads,%20Terrain,%20ATR

And check out this section of the FAQ: http://matlab.wikia.com/wiki/FAQ#Can_you_program_up_the_algorithm_in_this_article_for_me_and_explain_it_to_me.3F