ncnn

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// Tencent is pleased to support the open source community by making ncnn available.
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//
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// Copyright (C) 2021 THL A29 Limited, a Tencent company. All rights reserved.
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//
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// Licensed under the BSD 3-Clause License (the "License"); you may not use this file except
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// in compliance with the License. You may obtain a copy of the License at
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//
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// https://opensource.org/licenses/BSD-3-Clause
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//
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// Unless required by applicable law or agreed to in writing, software distributed
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// under the License is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
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// CONDITIONS OF ANY KIND, either express or implied. See the License for the
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// specific language governing permissions and limitations under the License.
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#include "net.h"
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#if defined(USE_NCNN_SIMPLEOCV)
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#include "simpleocv.h"
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#else
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#include <opencv2/core/core.hpp>
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#include <opencv2/highgui/highgui.hpp>
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#include <opencv2/imgproc/imgproc.hpp>
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#endif
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#include <stdio.h>
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#include <vector>
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struct FaceObject
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{
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    cv::Rect_<float> rect;
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    float prob;
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};
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static inline float intersection_area(const FaceObject& a, const FaceObject& b)
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{
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    cv::Rect_<float> inter = a.rect & b.rect;
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    return inter.area();
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}
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static void qsort_descent_inplace(std::vector<FaceObject>& faceobjects, int left, int right)
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{
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    int i = left;
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    int j = right;
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    float p = faceobjects[(left + right) / 2].prob;
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    while (i <= j)
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    {
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        while (faceobjects[i].prob > p)
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            i++;
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        while (faceobjects[j].prob < p)
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            j--;
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        if (i <= j)
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        {
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            // swap
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            std::swap(faceobjects[i], faceobjects[j]);
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            i++;
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            j--;
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        }
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    }
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    #pragma omp parallel sections
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    {
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        #pragma omp section
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        {
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            if (left < j) qsort_descent_inplace(faceobjects, left, j);
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        }
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        #pragma omp section
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        {
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            if (i < right) qsort_descent_inplace(faceobjects, i, right);
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        }
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    }
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}
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static void qsort_descent_inplace(std::vector<FaceObject>& faceobjects)
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{
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    if (faceobjects.empty())
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        return;
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    qsort_descent_inplace(faceobjects, 0, faceobjects.size() - 1);
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}
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static void nms_sorted_bboxes(const std::vector<FaceObject>& faceobjects, std::vector<int>& picked, float nms_threshold)
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{
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    picked.clear();
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    const int n = faceobjects.size();
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    std::vector<float> areas(n);
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    for (int i = 0; i < n; i++)
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    {
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        areas[i] = faceobjects[i].rect.area();
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    }
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    for (int i = 0; i < n; i++)
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    {
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        const FaceObject& a = faceobjects[i];
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        int keep = 1;
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        for (int j = 0; j < (int)picked.size(); j++)
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        {
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            const FaceObject& b = faceobjects[picked[j]];
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            // intersection over union
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            float inter_area = intersection_area(a, b);
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            float union_area = areas[i] + areas[picked[j]] - inter_area;
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            //             float IoU = inter_area / union_area
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            if (inter_area / union_area > nms_threshold)
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                keep = 0;
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        }
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        if (keep)
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            picked.push_back(i);
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    }
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}
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// insightface/detection/scrfd/mmdet/core/anchor/anchor_generator.py gen_single_level_base_anchors()
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static ncnn::Mat generate_anchors(int base_size, const ncnn::Mat& ratios, const ncnn::Mat& scales)
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{
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    int num_ratio = ratios.w;
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    int num_scale = scales.w;
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    ncnn::Mat anchors;
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    anchors.create(4, num_ratio * num_scale);
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    const float cx = 0;
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    const float cy = 0;
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    for (int i = 0; i < num_ratio; i++)
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    {
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        float ar = ratios[i];
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        int r_w = round(base_size / sqrt(ar));
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        int r_h = round(r_w * ar); //round(base_size * sqrt(ar));
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        for (int j = 0; j < num_scale; j++)
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        {
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            float scale = scales[j];
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            float rs_w = r_w * scale;
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            float rs_h = r_h * scale;
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            float* anchor = anchors.row(i * num_scale + j);
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            anchor[0] = cx - rs_w * 0.5f;
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            anchor[1] = cy - rs_h * 0.5f;
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            anchor[2] = cx + rs_w * 0.5f;
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            anchor[3] = cy + rs_h * 0.5f;
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        }
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    }
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    return anchors;
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}
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static void generate_proposals(const ncnn::Mat& anchors, int feat_stride, const ncnn::Mat& score_blob, const ncnn::Mat& bbox_blob, float prob_threshold, std::vector<FaceObject>& faceobjects)
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{
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    int w = score_blob.w;
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    int h = score_blob.h;
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    // generate face proposal from bbox deltas and shifted anchors
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    const int num_anchors = anchors.h;
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    for (int q = 0; q < num_anchors; q++)
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    {
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        const float* anchor = anchors.row(q);
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        const ncnn::Mat score = score_blob.channel(q);
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        const ncnn::Mat bbox = bbox_blob.channel_range(q * 4, 4);
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        // shifted anchor
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        float anchor_y = anchor[1];
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        float anchor_w = anchor[2] - anchor[0];
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        float anchor_h = anchor[3] - anchor[1];
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        for (int i = 0; i < h; i++)
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        {
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            float anchor_x = anchor[0];
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            for (int j = 0; j < w; j++)
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            {
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                int index = i * w + j;
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                float prob = score[index];
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                if (prob >= prob_threshold)
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                {
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                    // insightface/detection/scrfd/mmdet/models/dense_heads/scrfd_head.py _get_bboxes_single()
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                    float dx = bbox.channel(0)[index] * feat_stride;
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                    float dy = bbox.channel(1)[index] * feat_stride;
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                    float dw = bbox.channel(2)[index] * feat_stride;
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                    float dh = bbox.channel(3)[index] * feat_stride;
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                    // insightface/detection/scrfd/mmdet/core/bbox/transforms.py distance2bbox()
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                    float cx = anchor_x + anchor_w * 0.5f;
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                    float cy = anchor_y + anchor_h * 0.5f;
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                    float x0 = cx - dx;
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                    float y0 = cy - dy;
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                    float x1 = cx + dw;
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                    float y1 = cy + dh;
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                    FaceObject obj;
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                    obj.rect.x = x0;
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                    obj.rect.y = y0;
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                    obj.rect.width = x1 - x0 + 1;
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                    obj.rect.height = y1 - y0 + 1;
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                    obj.prob = prob;
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                    faceobjects.push_back(obj);
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                }
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                anchor_x += feat_stride;
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            }
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            anchor_y += feat_stride;
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        }
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    }
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}
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static int detect_scrfd(const cv::Mat& bgr, std::vector<FaceObject>& faceobjects)
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{
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    ncnn::Net scrfd;
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    scrfd.opt.use_vulkan_compute = true;
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    // model is converted from
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    // https://github.com/deepinsight/insightface/tree/master/detection/scrfd
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    // the ncnn model https://github.com/nihui/ncnn-assets/tree/master/models
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    if (scrfd.load_param("scrfd_500m-opt2.param"))
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        exit(-1);
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    if (scrfd.load_model("scrfd_500m-opt2.bin"))
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        exit(-1);
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    int width = bgr.cols;
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    int height = bgr.rows;
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    // insightface/detection/scrfd/configs/scrfd/scrfd_500m.py
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    const int target_size = 640;
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    const float prob_threshold = 0.3f;
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    const float nms_threshold = 0.45f;
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    // pad to multiple of 32
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    int w = width;
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    int h = height;
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    float scale = 1.f;
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    if (w > h)
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    {
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        scale = (float)target_size / w;
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        w = target_size;
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        h = h * scale;
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    }
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    else
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    {
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        scale = (float)target_size / h;
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        h = target_size;
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        w = w * scale;
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    }
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    ncnn::Mat in = ncnn::Mat::from_pixels_resize(bgr.data, ncnn::Mat::PIXEL_BGR2RGB, width, height, w, h);
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    // pad to target_size rectangle
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    int wpad = (w + 31) / 32 * 32 - w;
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    int hpad = (h + 31) / 32 * 32 - h;
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    ncnn::Mat in_pad;
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    ncnn::copy_make_border(in, in_pad, hpad / 2, hpad - hpad / 2, wpad / 2, wpad - wpad / 2, ncnn::BORDER_CONSTANT, 0.f);
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    const float mean_vals[3] = {127.5f, 127.5f, 127.5f};
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    const float norm_vals[3] = {1 / 128.f, 1 / 128.f, 1 / 128.f};
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    in_pad.substract_mean_normalize(mean_vals, norm_vals);
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    ncnn::Extractor ex = scrfd.create_extractor();
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    ex.input("input.1", in_pad);
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    std::vector<FaceObject> faceproposals;
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    // stride 32
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    {
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        ncnn::Mat score_blob, bbox_blob;
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        ex.extract("412", score_blob);
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        ex.extract("415", bbox_blob);
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        const int base_size = 16;
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        const int feat_stride = 8;
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        ncnn::Mat ratios(1);
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        ratios[0] = 1.f;
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        ncnn::Mat scales(2);
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        scales[0] = 1.f;
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        scales[1] = 2.f;
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        ncnn::Mat anchors = generate_anchors(base_size, ratios, scales);
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        std::vector<FaceObject> faceobjects32;
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        generate_proposals(anchors, feat_stride, score_blob, bbox_blob, prob_threshold, faceobjects32);
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        faceproposals.insert(faceproposals.end(), faceobjects32.begin(), faceobjects32.end());
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    }
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    // stride 16
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    {
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        ncnn::Mat score_blob, bbox_blob;
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        ex.extract("474", score_blob);
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        ex.extract("477", bbox_blob);
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        const int base_size = 64;
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        const int feat_stride = 16;
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        ncnn::Mat ratios(1);
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        ratios[0] = 1.f;
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        ncnn::Mat scales(2);
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        scales[0] = 1.f;
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        scales[1] = 2.f;
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        ncnn::Mat anchors = generate_anchors(base_size, ratios, scales);
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        std::vector<FaceObject> faceobjects16;
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        generate_proposals(anchors, feat_stride, score_blob, bbox_blob, prob_threshold, faceobjects16);
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        faceproposals.insert(faceproposals.end(), faceobjects16.begin(), faceobjects16.end());
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    }
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    // stride 8
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    {
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        ncnn::Mat score_blob, bbox_blob;
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        ex.extract("536", score_blob);
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        ex.extract("539", bbox_blob);
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        const int base_size = 256;
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        const int feat_stride = 32;
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        ncnn::Mat ratios(1);
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        ratios[0] = 1.f;
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        ncnn::Mat scales(2);
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        scales[0] = 1.f;
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        scales[1] = 2.f;
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        ncnn::Mat anchors = generate_anchors(base_size, ratios, scales);
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        std::vector<FaceObject> faceobjects8;
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        generate_proposals(anchors, feat_stride, score_blob, bbox_blob, prob_threshold, faceobjects8);
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        faceproposals.insert(faceproposals.end(), faceobjects8.begin(), faceobjects8.end());
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    }
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    // sort all proposals by score from highest to lowest
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    qsort_descent_inplace(faceproposals);
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    // apply nms with nms_threshold
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    std::vector<int> picked;
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    nms_sorted_bboxes(faceproposals, picked, nms_threshold);
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    int face_count = picked.size();
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    faceobjects.resize(face_count);
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    for (int i = 0; i < face_count; i++)
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    {
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        faceobjects[i] = faceproposals[picked[i]];
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        // adjust offset to original unpadded
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        float x0 = (faceobjects[i].rect.x - (wpad / 2)) / scale;
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        float y0 = (faceobjects[i].rect.y - (hpad / 2)) / scale;
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        float x1 = (faceobjects[i].rect.x + faceobjects[i].rect.width - (wpad / 2)) / scale;
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        float y1 = (faceobjects[i].rect.y + faceobjects[i].rect.height - (hpad / 2)) / scale;
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        x0 = std::max(std::min(x0, (float)width - 1), 0.f);
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        y0 = std::max(std::min(y0, (float)height - 1), 0.f);
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        x1 = std::max(std::min(x1, (float)width - 1), 0.f);
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        y1 = std::max(std::min(y1, (float)height - 1), 0.f);
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        faceobjects[i].rect.x = x0;
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        faceobjects[i].rect.y = y0;
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        faceobjects[i].rect.width = x1 - x0;
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        faceobjects[i].rect.height = y1 - y0;
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    }
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    return 0;
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}
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static void draw_faceobjects(const cv::Mat& bgr, const std::vector<FaceObject>& faceobjects)
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{
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    cv::Mat image = bgr.clone();
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    for (size_t i = 0; i < faceobjects.size(); i++)
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    {
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        const FaceObject& obj = faceobjects[i];
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        fprintf(stderr, "%.5f at %.2f %.2f %.2f x %.2f\n", obj.prob,
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                obj.rect.x, obj.rect.y, obj.rect.width, obj.rect.height);
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        cv::rectangle(image, obj.rect, cv::Scalar(0, 255, 0));
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        char text[256];
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        sprintf(text, "%.1f%%", obj.prob * 100);
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        int baseLine = 0;
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        cv::Size label_size = cv::getTextSize(text, cv::FONT_HERSHEY_SIMPLEX, 0.5, 1, &baseLine);
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        int x = obj.rect.x;
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        int y = obj.rect.y - label_size.height - baseLine;
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        if (y < 0)
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            y = 0;
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        if (x + label_size.width > image.cols)
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            x = image.cols - label_size.width;
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        cv::rectangle(image, cv::Rect(cv::Point(x, y), cv::Size(label_size.width, label_size.height + baseLine)),
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                      cv::Scalar(255, 255, 255), -1);
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        cv::putText(image, text, cv::Point(x, y + label_size.height),
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                    cv::FONT_HERSHEY_SIMPLEX, 0.5, cv::Scalar(0, 0, 0));
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    }
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    cv::imshow("image", image);
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    cv::waitKey(0);
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}
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int main(int argc, char** argv)
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{
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    if (argc != 2)
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    {
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        fprintf(stderr, "Usage: %s [imagepath]\n", argv[0]);
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        return -1;
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    }
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    const char* imagepath = argv[1];
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    cv::Mat m = cv::imread(imagepath, 1);
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    if (m.empty())
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    {
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        fprintf(stderr, "cv::imread %s failed\n", imagepath);
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        return -1;
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    }
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    std::vector<FaceObject> faceobjects;
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    detect_scrfd(m, faceobjects);
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    draw_faceobjects(m, faceobjects);
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    return 0;
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}
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