opencv/modules/photo/src/fast_nlmeans_multi_denoising_invoker.hpp

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#ifndef __OPENCV_FAST_NLMEANS_MULTI_DENOISING_INVOKER_HPP__
#define __OPENCV_FAST_NLMEANS_MULTI_DENOISING_INVOKER_HPP__

#include "precomp.hpp"
#include <limits>

#include "fast_nlmeans_denoising_invoker_commons.hpp"
#include "arrays.hpp"

using namespace cv;

template <typename T>
struct FastNlMeansMultiDenoisingInvoker : ParallelLoopBody {
    public:
        FastNlMeansMultiDenoisingInvoker(
            const std::vector<Mat>& srcImgs, int imgToDenoiseIndex, int temporalWindowSize,
            Mat& dst, int template_window_size, int search_window_size, const float h);

        void operator() (const Range& range) const;

    private:
        void operator= (const FastNlMeansMultiDenoisingInvoker&);

        int rows_;
        int cols_;

        Mat& dst_;

        std::vector<Mat> extended_srcs_;
        Mat main_extended_src_;
        int border_size_;

        int template_window_size_;
        int search_window_size_;
        int temporal_window_size_;

        int template_window_half_size_;
        int search_window_half_size_;
        int temporal_window_half_size_;

        int fixed_point_mult_;
        int almost_template_window_size_sq_bin_shift;
        std::vector<int> almost_dist2weight;

        void calcDistSumsForFirstElementInRow(
            int i,
            Array3d<int>& dist_sums,
            Array4d<int>& col_dist_sums,
            Array4d<int>& up_col_dist_sums) const;

        void calcDistSumsForElementInFirstRow(
            int i,
            int j,
            int first_col_num,
            Array3d<int>& dist_sums,
            Array4d<int>& col_dist_sums,
            Array4d<int>& up_col_dist_sums) const;
};

template <class T>
FastNlMeansMultiDenoisingInvoker<T>::FastNlMeansMultiDenoisingInvoker(
    const std::vector<Mat>& srcImgs,
    int imgToDenoiseIndex,
    int temporalWindowSize,
    cv::Mat& dst,
    int template_window_size,
    int search_window_size,
    const float h) : dst_(dst), extended_srcs_(srcImgs.size())
{
    CV_Assert(srcImgs.size() > 0);
    CV_Assert(srcImgs[0].channels() == sizeof(T));

    rows_ = srcImgs[0].rows;
    cols_ = srcImgs[0].cols;

    template_window_half_size_ = template_window_size / 2;
    search_window_half_size_ = search_window_size / 2;
    temporal_window_half_size_ = temporalWindowSize / 2;

    template_window_size_ = template_window_half_size_ * 2 + 1;
    search_window_size_ = search_window_half_size_ * 2 + 1;
    temporal_window_size_ = temporal_window_half_size_ * 2 + 1;

    border_size_ = search_window_half_size_ + template_window_half_size_;
    for (int i = 0; i < temporal_window_size_; i++) {
        copyMakeBorder(
            srcImgs[imgToDenoiseIndex - temporal_window_half_size_ + i], extended_srcs_[i],
            border_size_, border_size_, border_size_, border_size_, cv::BORDER_DEFAULT);
    }
    main_extended_src_ = extended_srcs_[temporal_window_half_size_];

    const int max_estimate_sum_value =
        temporal_window_size_ * search_window_size_ * search_window_size_ * 255;

    fixed_point_mult_ = std::numeric_limits<int>::max() / max_estimate_sum_value;

    // precalc weight for every possible l2 dist between blocks
    // additional optimization of precalced weights to replace division(averaging) by binary shift
    int template_window_size_sq = template_window_size_ * template_window_size_;
    almost_template_window_size_sq_bin_shift = 0;
    while (1 << almost_template_window_size_sq_bin_shift < template_window_size_sq) {
        almost_template_window_size_sq_bin_shift++;
    }

    int almost_template_window_size_sq = 1 << almost_template_window_size_sq_bin_shift;
    double almost_dist2actual_dist_multiplier =
        ((double) almost_template_window_size_sq) / template_window_size_sq;

    int max_dist = 255 * 255 * sizeof(T);
    int almost_max_dist = (int) (max_dist / almost_dist2actual_dist_multiplier + 1);
    almost_dist2weight.resize(almost_max_dist);

    const double WEIGHT_THRESHOLD = 0.001;
    for (int almost_dist = 0; almost_dist < almost_max_dist; almost_dist++) {
        double dist = almost_dist * almost_dist2actual_dist_multiplier;
        int weight = cvRound(fixed_point_mult_ * std::exp(-dist / (h * h * sizeof(T))));

        if (weight < WEIGHT_THRESHOLD * fixed_point_mult_) {
            weight = 0;
        }

        almost_dist2weight[almost_dist] = weight;
    }
    CV_Assert(almost_dist2weight[0] == fixed_point_mult_);
    // additional optimization init end

    if (dst_.empty()) {
        dst_ = Mat::zeros(srcImgs[0].size(), srcImgs[0].type());
    }
}

template <class T>
void FastNlMeansMultiDenoisingInvoker<T>::operator() (const Range& range) const {
    int row_from = range.start;
    int row_to = range.end - 1;

    Array3d<int> dist_sums(temporal_window_size_, search_window_size_, search_window_size_);

    // for lazy calc optimization
    Array4d<int> col_dist_sums(
        template_window_size_, temporal_window_size_, search_window_size_, search_window_size_);

    int first_col_num = -1;

    Array4d<int> up_col_dist_sums(
        cols_, temporal_window_size_, search_window_size_, search_window_size_);

    for (int i = row_from; i <= row_to; i++) {
        for (int j = 0; j < cols_; j++) {
            int search_window_y = i - search_window_half_size_;
            int search_window_x = j - search_window_half_size_;

            // calc dist_sums
            if (j == 0) {
                calcDistSumsForFirstElementInRow(i, dist_sums, col_dist_sums, up_col_dist_sums);
                first_col_num = 0;

            } else { // calc cur dist_sums using previous dist_sums
                if (i == row_from) {
                    calcDistSumsForElementInFirstRow(i, j, first_col_num,
                        dist_sums, col_dist_sums, up_col_dist_sums);

                } else {
                    int ay = border_size_ + i;
                    int ax = border_size_ + j + template_window_half_size_;

                    int start_by =
                        border_size_ + i - search_window_half_size_;

                    int start_bx =
                        border_size_ + j - search_window_half_size_ + template_window_half_size_;

                    T a_up = main_extended_src_.at<T>(ay - template_window_half_size_ - 1, ax);
                    T a_down = main_extended_src_.at<T>(ay + template_window_half_size_, ax);

                    // copy class member to local variable for optimization
                    int search_window_size = search_window_size_;

                    for (int d = 0; d < temporal_window_size_; d++) {
                        Mat cur_extended_src = extended_srcs_[d];
                        Array2d<int> cur_dist_sums = dist_sums[d];
                        Array2d<int> cur_col_dist_sums = col_dist_sums[first_col_num][d];
                        Array2d<int> cur_up_col_dist_sums = up_col_dist_sums[j][d];
                        for (int y = 0; y < search_window_size; y++) {
                            int* dist_sums_row = cur_dist_sums.row_ptr(y);

                            int* col_dist_sums_row = cur_col_dist_sums.row_ptr(y);

                            int* up_col_dist_sums_row = cur_up_col_dist_sums.row_ptr(y);

                            const T* b_up_ptr =
                                cur_extended_src.ptr<T>(start_by - template_window_half_size_ - 1 + y);
                            const T* b_down_ptr =
                                cur_extended_src.ptr<T>(start_by + template_window_half_size_ + y);

                            for (int x = 0; x < search_window_size; x++) {
                                dist_sums_row[x] -= col_dist_sums_row[x];

                                col_dist_sums_row[x] = up_col_dist_sums_row[x] +
                                    calcUpDownDist(
                                        a_up, a_down,
                                        b_up_ptr[start_bx + x], b_down_ptr[start_bx + x]
                                    );

                                dist_sums_row[x] += col_dist_sums_row[x];

                                up_col_dist_sums_row[x] = col_dist_sums_row[x];

                            }
                        }
                    }
                }

                first_col_num = (first_col_num + 1) % template_window_size_;
            }

            // calc weights
            int weights_sum = 0;

            int estimation[3];
            for (size_t channel_num = 0; channel_num < sizeof(T); channel_num++) {
                estimation[channel_num] = 0;
            }
            for (int d = 0; d < temporal_window_size_; d++) {
                const Mat& esrc_d = extended_srcs_[d];
                for (int y = 0; y < search_window_size_; y++) {
                    const T* cur_row_ptr = esrc_d.ptr<T>(border_size_ + search_window_y + y);

                    int* dist_sums_row = dist_sums.row_ptr(d, y);

                    for (int x = 0; x < search_window_size_; x++) {
                        int almostAvgDist =
                            dist_sums_row[x] >> almost_template_window_size_sq_bin_shift;

                        int weight = almost_dist2weight[almostAvgDist];
                        weights_sum += weight;

                        T p = cur_row_ptr[border_size_ + search_window_x + x];
                        incWithWeight(estimation, weight, p);
                    }
                }
            }

            for (size_t channel_num = 0; channel_num < sizeof(T); channel_num++)
                estimation[channel_num] = ((unsigned)estimation[channel_num] + weights_sum / 2) / weights_sum;

            dst_.at<T>(i,j) = saturateCastFromArray<T>(estimation);

        }
    }
}

template <class T>
inline void FastNlMeansMultiDenoisingInvoker<T>::calcDistSumsForFirstElementInRow(
    int i,
    Array3d<int>& dist_sums,
    Array4d<int>& col_dist_sums,
    Array4d<int>& up_col_dist_sums) const
{
    int j = 0;

    for (int d = 0; d < temporal_window_size_; d++) {
        Mat cur_extended_src = extended_srcs_[d];
        for (int y = 0; y < search_window_size_; y++) {
            for (int x = 0; x < search_window_size_; x++) {
                dist_sums[d][y][x] = 0;
                for (int tx = 0; tx < template_window_size_; tx++) {
                    col_dist_sums[tx][d][y][x] = 0;
                }

                int start_y = i + y - search_window_half_size_;
                int start_x = j + x - search_window_half_size_;

                int* dist_sums_ptr = &dist_sums[d][y][x];
                int* col_dist_sums_ptr = &col_dist_sums[0][d][y][x];
                int col_dist_sums_step = col_dist_sums.step_size(0);
                for (int tx = -template_window_half_size_; tx <= template_window_half_size_; tx++) {
                    for (int ty = -template_window_half_size_; ty <= template_window_half_size_; ty++) {
                        int dist = calcDist<T>(
                            main_extended_src_.at<T>(
                                border_size_ + i + ty, border_size_ + j + tx),
                            cur_extended_src.at<T>(
                                border_size_ + start_y + ty, border_size_ + start_x + tx)
                        );

                        *dist_sums_ptr += dist;
                        *col_dist_sums_ptr += dist;
                    }
                    col_dist_sums_ptr += col_dist_sums_step;
                }

                up_col_dist_sums[j][d][y][x] = col_dist_sums[template_window_size_ - 1][d][y][x];
            }
        }
    }
}

template <class T>
inline void FastNlMeansMultiDenoisingInvoker<T>::calcDistSumsForElementInFirstRow(
    int i,
    int j,
    int first_col_num,
    Array3d<int>& dist_sums,
    Array4d<int>& col_dist_sums,
    Array4d<int>& up_col_dist_sums) const
{
    int ay = border_size_ + i;
    int ax = border_size_ + j + template_window_half_size_;

    int start_by = border_size_ + i - search_window_half_size_;
    int start_bx = border_size_ + j - search_window_half_size_ + template_window_half_size_;

    int new_last_col_num = first_col_num;

    for (int d = 0; d < temporal_window_size_; d++) {
        Mat cur_extended_src = extended_srcs_[d];
        for (int y = 0; y < search_window_size_; y++) {
            for (int x = 0; x < search_window_size_; x++) {
                dist_sums[d][y][x] -= col_dist_sums[first_col_num][d][y][x];

                col_dist_sums[new_last_col_num][d][y][x] = 0;
                int by = start_by + y;
                int bx = start_bx + x;

                int* col_dist_sums_ptr = &col_dist_sums[new_last_col_num][d][y][x];
                for (int ty = -template_window_half_size_; ty <= template_window_half_size_; ty++) {
                    *col_dist_sums_ptr +=
                        calcDist<T>(
                            main_extended_src_.at<T>(ay + ty, ax),
                            cur_extended_src.at<T>(by + ty, bx)
                        );
                }

                dist_sums[d][y][x] += col_dist_sums[new_last_col_num][d][y][x];

                up_col_dist_sums[j][d][y][x] = col_dist_sums[new_last_col_num][d][y][x];
            }
        }
    }
}

#endif