Histogram Drawing Function

Image draw_hist(Image src) {  // HISTOGRAM DRAWING
    Image histogram = Image(100, 256);

    // Making hist_img null;
    for (int i = 0; i < histogram.n_rows; i++) {
        for (int j = 0; j < histogram.n_cols; j++) {
            std::get<0>(histogram(i,j)) = 0;
            std::get<1>(histogram(i,j)) = 0;
            std::get<2>(histogram(i,j)) = 0;

        }
    }

    int freq[256] = {0};
    int r_freq[256] = {0};
    int g_freq[256] = {0};
    int b_freq[256] = {0};


    int avg = 0;
    for (int row = 0; row < src.n_rows; row++) {
        for (int col = 0; col < src.n_cols; col++) {
            avg = (int) ((std::get<0>(src(row, col)) + std::get<1>(src(row, col)) + std::get<2>(src(row, col))) / 3);
            freq[avg]++;
            r_freq[(std::get<0>(src(row, col)))]++;
            g_freq[(std::get<1>(src(row, col)))]++;
            b_freq[(std::get<2>(src(row, col)))]++;

        }
    }

    int max = 0;
    for (auto &x : freq) { if (x > max) max = x; }

    // CODE BELOW IS USED FOR SETTING UP HIST IMAGE.
    // NOTHING INTERESTING HERE. I MEAN RLY.


    for (auto &x : freq) { if (x > max) max = x; }
    for (auto &x : r_freq) { x = (int)(((double)x / max) * 90); }
    for (auto &x : g_freq) { x = (int)(((double)x / max) * 90); }
    for (auto &x : b_freq) { x = (int)(((double)x / max) * 90); }


    for (int x = 0; x < 256; x++) {
        for (int c = 90; c > 90 - r_freq[x]; c--) {
            std::get<0>(histogram(c, x)) = 255;
        }
    }

    for (int x = 0; x < 256; x++) {
        for (int c = 90; c > 90 - g_freq[x]; c--) {
            std::get<1>(histogram(c, x)) = 255;
        }
    }

    for (int x = 0; x < 256; x++) {
        for (int c = 90; c > 90 - b_freq[x]; c--) {
            std::get<2>(histogram(c, x)) = 255;
        }
    }

    return histogram;
}