Function psnr

dlib/test/ffmpeg.cpp:120–136

    template <typename pixel_type>
    static double psnr(const matrix<pixel_type>& img1, const matrix<pixel_type>& img2)
    {
        DLIB_TEST(have_same_dimensions(img1, img2));
        const long nk           = width_step(img1) / img1.nc();
        const long data_size    = img1.size() * nk;
        auto* data1             = reinterpret_cast<const uint8_t*>(image_data(img1));
        auto* data2             = reinterpret_cast<const uint8_t*>(image_data(img2));

        double mse = 0;
        for (long i = 0; i < data_size; i += nk)
        {
            for (long k = 0; k < nk; ++k)
                mse += std::pow(static_cast<double>(data1[i + k]) - static_cast<double>(data2[i + k]), 2);
        }
        mse /= data_size;
        return 20 * std::log10(pixel_traits<pixel_type>::max()) - 10 * std::log10(mse);
    }

    void test_load_frame(const std::string& filename)
    {