사용한 라이브러리

Q.22. 히스토그램 조작

int main()
{
    PPM ppm("imori_dark.pnm");
    int width = ppm.Get_width();
    int height = ppm.Get_height();

    int N = 256;
    std::vector<int> hist(N);
    for (int n = 0; n < N; n++)
    {
        hist[n] = 0;
    }

    double m = 0;
    double m2 = 0;
    for (int j = 0; j < height; j++)
        for (int i = 0; i < width; i++)
        {
            m += ppm(i, j, 'r');
            m += ppm(i, j, 'g');
            m += ppm(i, j, 'b');
            m2 += ppm(i, j, 'r')* ppm(i, j, 'r');
            m2 += ppm(i, j, 'g')* ppm(i, j, 'g');
            m2 += ppm(i, j, 'b')* ppm(i, j, 'b');


        }
    m /= (double)(width * height * 3);
    m2 /= (double)(width * height * 3);
    double s2 = m2 - m * m;
    double s = sqrt(s2);

    PPM ppm2(width, height);
    double m0 = 128;
    double s0 = 52;
    for (int j = 0; j < height; j++)
        for (int i = 0; i < width; i++)
        {
            double a;
            a = s0 / s * (ppm(i, j, 'r') - m) + m0;
            if (a < 0) a = 0;
            else if (a >= N) a = N - 1;
            ppm2(i, j, 'r') = a;
            hist[a]++;

            a = s0 / s * (ppm(i, j, 'g') - m) + m0;
            if (a < 0) a = 0;
            else if (a >= N) a = N - 1;
            ppm2(i, j, 'g') = a;
            hist[a]++;

            a = s0 / s * (ppm(i, j, 'b') - m) + m0;
            if (a < 0) a = 0;
            else if (a >= N) a = N - 1;
            ppm2(i, j, 'b') = a;
            hist[a]++;



        }
    for (int n = 0; n < N; n++)
    {
        std::cout << n << " " << hist[n] << std::endl;
    }
    ppm2.Flush("out.ppm");




    return 0;
}