Matlab - Watershed for Line Extraction - Lost Information

Question

I have an image of a vein as shown below. I use the watershed algorithm to extract the skeleton of a vein.

My code: (K is the original image).

level = graythresh(K);
BW = im2bw(K,level);
D = bwdist(~BW);
DL = watershed(D);
bgm = DL == 0;
imshow(bgm);

Result:

As you can see, a lot of information is lost. Can anybody help me? Thank.

Answer 1

, . . , , , ( ). , , , .

%# Load image and convert to [0,1].
A = im2double(imread('http://i.stack.imgur.com/TQp1i.png'));
%# Any large (relative to objects) structuring element will do.
%# Try sizes up to about half of the image size.
se = strel('square',32);
%# Removes uneven lighting and enhances contrast.
B = imdivide(A,imclose(A,se));
%# Otsu method works well now.
C = B > graythresh(B);
D = bwdist(~C);
DL = watershed(D);
imshow(DL==0);

C (), DL==0 ( ) :

Answer 2

, ( , Otsu). , , , . , , .

, -

w=gausswin(N,Alpha)  % you'll have to play with N and alpha
K = imfilter(K,w,'same','symmetric'); % something like these options

.

Answer 3

, , im2bw, uint8, intmin('uint8')==0 intmax('uint8')==255, ( logical). , , . BW, , K, level, , , , .