Function normalizeDesc

src/backend/cpu/kernel/sift.hpp:502–510

}

void normalizeDesc(float* desc, const int histlen) {
    float len_sq = 0.0f;

    for (int i = 0; i < histlen; i++) len_sq += desc[i] * desc[i];

    float len_inv = 1.0f / sqrt(len_sq);

    for (int i = 0; i < histlen; i++) { desc[i] *= len_inv; }
}

// Computes feature descriptors for features in an array.  Based on Section 6
// of Lowe's paper.