Hi,
As I can understand you are trying to extract cracks from a tomography image. You tried several ways to enhance the colours of image, but some some cracks are still missing.
For better crack extraction from the image, you can perform following changes in your code –
1. Enhance contrast using adaptive histogram equalization
A = adapthisteq(A);
2. Apply Gaussian smoothing to reduce noise
A = imgaussfilt(A, 2);
3. Set the threshold value to 52 for better results
Here is the updated code snippet –
clear all
close all
clc
A= imread('image_1567.png');
A = adapthisteq(A);
A = imgaussfilt(A, 2);
[rows, columns, numberOfColorChannels] = size(A);
[centers,radii] = imfindcircles(A,[500 650],Sensitivity=0.95);
mask = circles2mask(centers,radii,size(A));
new_image = A;
new_image(~mask) = nan;
figure(1)
sigma = 20;
Iflatfield = imflatfield(new_image,sigma);
imshow(Iflatfield)
figure(2)
imhist(Iflatfield);
figure(3)
crackMask = Iflatfield < 52;
imshow(crackMask)
Attaching the documentation of above used functions for reference -
