Separation of rice grains . I want to separate out the grains that are darker in the image.

The image contains rice grains. I want to separate out the darker rice grains in image 'Main'. I have marked the ones which needed to be separate out in attachment 'Result'. I also want to count the no. of lighter and darker grians. I know the image has a lot of noise because i captured the grains by keeping them on laptop screen. Apologies for that.

Answer 1

[DGM]

Segmentation might be a bit easier with a bit of a diffuser to deal with the bg. The median filter (or just downscaling the image) helps deal with it in this case.

A = imread('https://www.mathworks.com/matlabcentral/answers/uploaded_files/905805/Main.jpg');
A = rgb2gray(A);
A = medfilt2(A,[10 10]);

mask = imclearborder(A<150);
mask = bwareaopen(mask,2000);

imshow(mask)

S = regionprops(mask,A,'meanintensity','centroid');
C = vertcat(S.Centroid);
graincolor = vertcat(S.MeanIntensity);
grainmask = graincolor<60; 

figure
imshow(A); hold on
for b = 1:numel(S)
    if grainmask(b)
        plot(C(b,1),C(b,2),'bo','markersize',25);
    else
        plot(C(b,1),C(b,2),'ro','markersize',25);
    end
end