Stack images with opencv

Per ridurre il rumore, come si fa in astrofotografia, un sistema semplice per fare stacking

 

g++ stack_images.cpp -o stack_images `pkg-config --cflags --libs opencv4` -std=c++17

 stack_images.cpp

#include <opencv2/opencv.hpp>

#include <filesystem>

#include <vector>

#include <iostream>

namespace fs = std::filesystem;

int main() {

std::string folder = "images"; // Folder containing your PNGs

std::vector<cv::Mat> images;

// Load all PNGs from folder

for (const auto& entry : fs::directory_iterator(folder)) {

if (entry.path().extension() == ".png") {

cv::Mat img = cv::imread(entry.path().string(), cv::IMREAD_UNCHANGED);

if (!img.empty()) {

images.push_back(img);

std::cout << "Loaded: " << entry.path() << std::endl;

}

}

}

if (images.empty()) {

std::cerr << "No images loaded!" << std::endl;

return 1;

}

// Use first image size/type as reference

cv::Size imgSize = images[0].size();

int imgType = images[0].type();

// Convert all to CV_32F or CV_32FCn for precision

cv::Mat accumulator = cv::Mat::zeros(imgSize, CV_MAKETYPE(CV_32F, images[0].channels()));

for (const auto& img : images) {

cv::Mat imgFloat;

img.convertTo(imgFloat, CV_32F);

accumulator += imgFloat;

}

// Compute average

accumulator /= static_cast<float>(images.size());

// Convert back to original depth

cv::Mat result;

accumulator.convertTo(result, images[0].type());

// Save result

cv::imwrite("stacked_avg.png", result);

std::cout << "Saved stacked image as stacked_avg.png" << std::endl;

cv::Mat claheResult;

if (result.channels() == 3) {

// Convert to Lab color space

cv::Mat lab;

cv::cvtColor(result, lab, cv::COLOR_BGR2Lab);

std::vector<cv::Mat> lab_planes;

cv::split(lab, lab_planes);

// CLAHE on L channel

cv::Ptr<cv::CLAHE> clahe = cv::createCLAHE();

clahe->setClipLimit(2.0);

clahe->apply(lab_planes[0], lab_planes[0]);

// Merge and convert back

cv::merge(lab_planes, lab);

cv::cvtColor(lab, claheResult, cv::COLOR_Lab2BGR);

} else {

// Grayscale CLAHE

cv::Ptr<cv::CLAHE> clahe = cv::createCLAHE();

clahe->setClipLimit(2.0);

clahe->apply(result, claheResult);

}

cv::imwrite("stacked_avg_clahe.png", claheResult);

return 0;

}