void processImage(const char* inputFilename, const char* outputFilename, float sigma)
{
    // Load the input image
    std::vector<unsigned char> image;
    unsigned int width, height;
    unsigned error = lodepng::decode(image, width, height, inputFilename);
    if (error)
    {
        std::cerr << "Error decoding PNG: " << lodepng_error_text(error) << std::endl;
        return;
    }

    // Apply the Gaussian blur filter
    gaussianBlur(image.data(), width, height, 4, sigma);

    // Save the output image
    error = lodepng::encode(outputFilename, image, width, height);
    if (error)
    {
        std::cerr << "Error encoding PNG: " << lodepng_error_text(error) << std::endl;
        return;
    }

    std::cout << "Image processed successfully!" << std::endl;
}