[Rtk-users] How is the lagcorrection factor calculated? I always get some ambiguity when I do matlab calculations. Are there any examples of calculations

[.]

How is the lagcorrection factor calculated? I always get some ambiguity when I do matlab calculations. Are there any examples of calculations









I tried to implement it myself with matlab but I didn't get very good results. Do I need to normalize the input data in the program


Here is my matlab code I want to implement the fitting coefficient of FSRF But it didn't work out well


% Using ImageJ for operations:% 1. Extract the last 10 frames of the open exposure, convert to 32-bit, compute the average, draw ROI, measure, and save as an Excel file
% 2. Extract the stack for the dark field, convert to 32-bit, draw ROI, use multi-measure, and save as an Excel file
% 3. Split the stack and merge the stack
% 4. Combine into one Excel file with open exposure data first and dark field data following
% 5. Copy the mean to a .txt file
% Result: mean.txt


mean2 = table2array(mean); % Convert imported table type to array type
m = mean2(1);
n = mean2(2:end);
nm = n / m;


% Normalization
FSRF = nm;


x = 1:510; % Number of dark field frames
x = x';
y = FSRF; % Dark field data


% Fitting function
fitfunc = @(params, x) (params(1) * exp(-params(2) * x) + params(3) * exp(-params(4) * x) + params(5) * exp(-params(6) * x) + params(7) * exp(-params(8) * x));
initialGuess = [7e-3, 0.001, 1e-2, 0.01, 1e-2, 0.08, 3e-2, 0.6]; % Initial values


paramsFit = lsqcurvefit(fitfunc, initialGuess, x, y);
B1_fit = paramsFit(1);
A1_fit = paramsFit(2);
B2_fit = paramsFit(3);
A2_fit = paramsFit(4);
B3_fit = paramsFit(5);
A3_fit = paramsFit(6);
B4_fit = paramsFit(7);
A4_fit = paramsFit(8);


y_fit = fitfunc(paramsFit, x);
plot(x, y, 'ro', x, y_fit, 'b-');
grid on
legend('Sample Data', 'Fitted Curve');


save AB.mat A1_fit A2_fit A3_fit A4_fit B1_fit B2_fit B3_fit B4_fit




Here is the program I used to fit the coefficients in matlab into c++


// TaoSunLagCorrectionTest.cpp : Defines the entry point for the console application.//


#include "stdafx.h"
#include "TaoSunLagCorrection.h"
#include "rtkLagCorrectionImageFilter.h"
#include <chrono> // For timing
#include <fstream> // For file operations


// Suppress fopen warnings
#pragma warning(disable:4996)


int main()
{
    int height = 1328;
    int width = 1024;
    int angles = 360;


    //-------------------- Read projection data ----------------
    FILE* file1;
    const char* filename1 = "E:/TaoSunCUDA12/LagCorrection/data/Stack50-409_110kv 15macu 0.5mm 50hz - CT Phantom - full-fan.raw";


    // Buffer to store read data
    float* proj1 = (float*)malloc(height * width * angles * sizeof(float));
    if (proj1 == NULL)
    {
        printf("Memory allocation failed.\n");
        return -1;
    }


    file1 = fopen(filename1, "rb");
    if (file1 == NULL)
    {
        printf("Cannot open file %s\n", filename1);
        return -1;
    }


    // Read data from file into memory (vector)
    printf("Starting to read projection ... \n");
    fread(proj1, sizeof(float), height * width * angles, file1);
    fclose(file1);




    //--------------------- Correction ----------------------
    float* projoutput = (float*)malloc(height * width * angles * sizeof(float));


    // Start timing
    auto start_time = std::chrono::high_resolution_clock::now();


    // Lag correction parameters: detector (inherent characteristics), frame rate (default binning mode)
    printf("Starting lag correction ... \n");
    float m_A[4] = { 0.7055f, 0.141f, 0.0212f, 0.0033f };
    float m_B[4] = { 2.911e-3f, 0.4454e-3f, 0.0748e-3f, 0.0042e-3f };
    taoSun_LagCorrection(projoutput, proj1, m_A, m_B, height, width, angles);




    // End timing
    auto end_time = std::chrono::high_resolution_clock::now();


    // Output elapsed time
    std::chrono::duration<double> elapsed = end_time - start_time;
    std::cout << "Total execution time: " << elapsed.count() << " seconds" << std::endl;


    // After processing all projections, write the large memory data to a file in one go
    printf("Starting to write corrected projection ... \n");
    std::ofstream outputFile("E:/TaoSunCUDA12/LagCorrection/data/output0902.raw", std::ios::binary); // Open a new raw file for writing processed data
    if (!outputFile.is_open())
    {
        std::cerr << "Error: Cannot open output raw file!" << std::endl;
        return EXIT_FAILURE;
    }
    size_t totalSize = angles * height * width * sizeof(float);  // Pre-calculate total memory required for all projection data
    outputFile.write(reinterpret_cast<const char*>(projoutput), totalSize);
    outputFile.close(); // Close the file  


    // Release the large allocated memory
    free(projoutput);
    free(proj1);


    std::cout << "\n\nTest PASSED! " << std::endl;


    return 0;
}
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.creatis.insa-lyon.fr/pipermail/rtk-users/attachments/20241101/5a7b5d8f/attachment.htm>