>> img = imread('pic.jpg');
>> figure, imshow(img)
>> b = rgb2gray(img);
>> figure, imshow (b),title('original image in grayscale')

>> c = 255-b;
>> figure, imshow(c);title('complemented original image in grayscale')

>> d = im2bw(c);
>> figure, imshow(d),title('Original image in black and white')

>> e = imfill(d,'holes');
>> figure, imshow(e),title('Fill image in black and white')

>> f = bwlabel(e);
>> figure, imshow(f),title('Labelled image in black and white')

>> vislabels(f),title('Each object labelled')
>> g = regionprops(f, 'Area', 'BoundingBox');
>> g(1)
>> area_values = [g.Area]
>> idx = find((6000 <= area_values) & (area_values <= 6500))
>> h = ismember(f, idx);
>> [h,num2] = bwlabel(h);
>> figure, imshow(h), title(['tangle number: ' num2str(num2) ''])