Watershed segmentation algorithm for segmenting occluded leaves in matlab

Question

The main task is to eliminate the complicated background of a leaf and extract the targeted leaf from an occluded leaf image in MATLAB. To eliminate the background i have applied K-means clustering algo. Now the main task is to segment the leaf from an occluded leaf using watershed segmentation algorithm. I am not able to find the perfect segments for every single leaf. Please help me. I have uploaded the sample images and also watershed segmentation code.

ORIGINAL IMAGE

Image after eliminating background using K-Means clustering algorithm and watershed Segmentation superimposed on original image

I want the main middle leaf to be a single segment, so that i can extract it.

I have given the watershed segmentation code below

function wateralgo(img)

F=imread(img);

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');
end

Answer 1

I think you should try a foreground extraction algorithm rather than a general segmentation. One such algorithm is GrabCut. Another thing that be helpful is to achieve some level of illumination variance in your image representation prior to trying to extract the foreground object. One way to do so is to work in the Chong color space.