How can I get this code to show only the veins in a fundus image of an eye ?

I have been trying to run a code in order to extract the retinal veins fromt he fundus image of an eye however it keeps giving me such erroneous output. I am including the part for extracting veins , however I am unsure so as to what is going wrong with this.

Code:

Coloured = imread('fundus_image');

Converted_Image = im2double(Coloured);

Lab_Image = rgb2lab(Converted_Image);

fill = cat(3, 1,0,0);

Filled_Image = bsxfun(@times, fill, Lab_Image);

Reshaped_Lab_Image = reshape(Filled_Image, [], 3);

[C, S] = pca(Reshaped_Lab_Image);

S = reshape(S, size(Lab_Image));

S = S(:, :, 1);

Gray_Image = (S-min(S(:)))./(max(S(:))-min(S(:)));

Enhanced_Image = adapthisteq(Gray_Image, 'numTiles', [8 8], 'nBins', 256);

Avg_Filter = fspecial('average', [9 9]);

Filtered_Image = imfilter(Enhanced_Image, Avg_Filter);

Substracted_Image = imsubtract(Filtered_Image,Enhanced_Image);

Image = im2uint8(Substracted_Image(:));

[Histogram_Count,Bin_Number]=imhist(Image);

i = 1;

Cumulative_Sum = cumsum(Histogram_Count);

T(i) = (sum(Bin_Number.*Histogram_Count))/Cumulative_Sum(end);

T(i)=round(T(i));

Cumulative_Sum_2 = cumsum(Histogram_Count(1:T(i)));

MBT=sum(Bin_Number(1:T(i)).*Histogram_Count(1:T(i)))/Cumulative_Sum_2(end);

Cumulative_Sum_3=cumsum(Histogram_Count(T(i):end));

MAT=sum(Bin_Number(T(i):end).*Histogram_Count(T(i):end))/Cumulative_Sum_3(end);

i = i+1;

T(i) = round((MAT+MBT)/2);

while abs(T(i)-T(i-1))>=1

Cumulative_Sum_2 = cumsum(Histogram_Count(1:T(i)));

MBT=sum(Bin_Number(1:T(i)).*Histogram_Count(1:T(i)))/Cumulative_Sum_2(end);

Cumulative_Sum_3=cumsum(Histogram_Count(T(i):end));

MAT=sum(Bin_Number(T(i):end).*Histogram_Count(T(i):end))/Cumulative_Sum_3(end);

i = i+1;

T(i) = round((MAT+MBT)/2);

Threshold = T(i);

end

level = (Threshold - 1) / (Bin_Number(end) - 1);

Binary_Image = imbinarize(Substracted_Image, level-0.008);

Clean_Image = bwareaopen(Binary_Image, 100);

figure, imshow(Clean_Image);

--> Any help is most appreciated.

Answer 1

[Image Analyst]

See https://www.mathworks.com/matlabcentral/fileexchange/49172-trainable-cosfire-filters-for-curvilinear-structure-delineation-in-images

or

https://www.mathworks.com/matlabcentral/fileexchange/24409-hessian-based-frangi-vesselness-filter