YOLOv4对检测到的目标进行计数

主要修改的image.c文件，在darknet目录下直接ctrl+f搜即可，然后打开，找到draw_detections_v3函数，加入用来计数的变量。

更新一下我的：
原作者的有问题。

//测试时检测图片使用的函数,视频不是这个
void draw_detections_v3(image im, detection *dets, int num, float thresh, char **names, image **alphabet, int classes, int ext_output)
{
    static int frame_id = 0;
    frame_id++;

    int selected_detections_num;
    detection_with_class* selected_detections = get_actual_detections(dets, num, thresh, &selected_detections_num, names);

    // text output
    qsort(selected_detections, selected_detections_num, sizeof(*selected_detections), compare_by_lefts);
    int i;
    for (i = 0; i < selected_detections_num; ++i) {
        const int best_class = selected_detections[i].best_class;
        printf("%s: %.0f%%", names[best_class], selected_detections[i].det.prob[best_class] * 100);
        if (ext_output)
            printf("\t(left_x: %4.0f   top_y: %4.0f   width: %4.0f   height: %4.0f)\n",
                round((selected_detections[i].det.bbox.x - selected_detections[i].det.bbox.w / 2)*im.w),
                round((selected_detections[i].det.bbox.y - selected_detections[i].det.bbox.h / 2)*im.h),
                round(selected_detections[i].det.bbox.w*im.w), round(selected_detections[i].det.bbox.h*im.h));
        else
            printf("\n");
        int j;
        for (j = 0; j < classes; ++j) {
            if (selected_detections[i].det.prob[j] > thresh && j != best_class) {
                printf("%s: %.0f%%", names[j], selected_detections[i].det.prob[j] * 100);

                if (ext_output)
                    printf("\t(left_x: %4.0f   top_y: %4.0f   width: %4.0f   height: %4.0f)\n",
                        round((selected_detections[i].det.bbox.x - selected_detections[i].det.bbox.w / 2)*im.w),
                        round((selected_detections[i].det.bbox.y - selected_detections[i].det.bbox.h / 2)*im.h),
                        round(selected_detections[i].det.bbox.w*im.w),
                        round(selected_detections[i].det.bbox.h*im.h));
                else
                    printf("\n");
            }
        }
    }

    // image output
    //检测的图片输出
    qsort(selected_detections, selected_detections_num, sizeof(*selected_detections), compare_by_probs);
    //修改
    //添加计数
    int count_studentDesk = 0;
    //====
    for (i = 0; i < selected_detections_num; ++i) {
            int width = im.h * .002;
            if (width < 1)
                width = 1;

            /*
            if(0){
            width = pow(prob, 1./2.)*10+1;
            alphabet = 0;
            }
            */

            //printf("%d %s: %.0f%%\n", i, names[selected_detections[i].best_class], prob*100);
            int offset = selected_detections[i].best_class * 123457 % classes;
            float red = get_color(2, offset, classes);
            float green = get_color(1, offset, classes);
            float blue = get_color(0, offset, classes);
            float rgb[3];

            //width = prob*20+2;

            rgb[0] = red;
            rgb[1] = green;
            rgb[2] = blue;
            box b = selected_detections[i].det.bbox;
            //printf("%f %f %f %f\n", b.x, b.y, b.w, b.h);

            int left = (b.x - b.w / 2.)*im.w;
            int right = (b.x + b.w / 2.)*im.w;
            int top = (b.y - b.h / 2.)*im.h;
            int bot = (b.y + b.h / 2.)*im.h;

            if (left < 0) left = 0;
            if (right > im.w - 1) right = im.w - 1;
            if (top < 0) top = 0;
            if (bot > im.h - 1) bot = im.h - 1;

            //int b_x_center = (left + right) / 2;
            //int b_y_center = (top + bot) / 2;
            //int b_width = right - left;
            //int b_height = bot - top;
            //sprintf(labelstr, "%d x %d - w: %d, h: %d", b_x_center, b_y_center, b_width, b_height);

            // you should create directory: result_img
            //static int copied_frame_id = -1;
            //static image copy_img;
            //if (copied_frame_id != frame_id) {
            //    copied_frame_id = frame_id;
            //    if (copy_img.data) free_image(copy_img);
            //    copy_img = copy_image(im);
            //}
            //image cropped_im = crop_image(copy_img, left, top, right - left, bot - top);
            //static int img_id = 0;
            //img_id++;
            //char image_name[1024];
            //int best_class_id = selected_detections[i].best_class;
            //sprintf(image_name, "result_img/img_%d_%d_%d_%s.jpg", frame_id, img_id, best_class_id, names[best_class_id]);
            //save_image(cropped_im, image_name);
            //free_image(cropped_im);

            //修改
            char studentDesk[30]; //左上角第一行字符串
            //=====

            if (im.c == 1) {
                draw_box_width_bw(im, left, top, right, bot, width, 0.8);    // 1 channel Black-White
            }
            else {
                draw_box_width(im, left, top, right, bot, width, red, green, blue); // 3 channels RGB
            }
            if (alphabet) {
                char labelstr[4096] = { 0 };
                strcat(labelstr, names[selected_detections[i].best_class]);
                char prob_str[10];
                sprintf(prob_str, ": %.2f", selected_detections[i].det.prob[selected_detections[i].best_class]);
                strcat(labelstr, prob_str);
                int j;
                for (j = 0; j < classes; ++j) {
                    if (selected_detections[i].det.prob[j] > thresh && j != selected_detections[i].best_class) {
                        strcat(labelstr, ", ");
                        strcat(labelstr, names[j]);
                    }
                }


                if (!strcmp(names[selected_detections->best_class], "studentDesk")) {
                    count_studentDesk++; //计数
                }

                image label = get_label_v3(alphabet, labelstr, (im.h*.02));
                //draw_label(im, top + width, left, label, rgb);
                draw_weighted_label(im, top + width, left, label, rgb, 0.7); //在每个BBox上显示标签和置信度
                free_image(label);
            }
            if (selected_detections[i].det.mask) {
                image mask = float_to_image(14, 14, 1, selected_detections[i].det.mask);
                image resized_mask = resize_image(mask, b.w*im.w, b.h*im.h);
                image tmask = threshold_image(resized_mask, .5);
                embed_image(tmask, im, left, top);
                free_image(mask);
                free_image(resized_mask);
                free_image(tmask);
            }

            //修改
            if (i == (selected_detections_num - 1)) {
                sprintf(studentDesk, "studentDesk_num:%d", count_studentDesk);
            }
            if (count_studentDesk)  //为0不显示
            {
                image label_studentDesk = get_label_v3(alphabet, studentDesk, (im.h * .03)); //最后一个参数是尺寸
                            //draw_label(im, 100, 150, label_studentDesk, rgb); //显示函数
                draw_weighted_label(im, 100, 150, label_studentDesk, rgb, 0.7);  //利用绘制标签函数在图像上显示计数
                free_image(label_studentDesk);
            }
            //image label_studentDesk = get_label_v3(alphabet, studentDesk, (im.h * .03)); //最后一个参数是尺寸
            //                //draw_label(im, 100, 150, label_studentDesk, rgb); //显示函数
            //draw_weighted_label(im, 100, 150, label_studentDesk, rgb, 0.7);  //利用绘制标签函数在图像上显示计数
            //free_image(label_studentDesk);
            //---------------------

    }
    free(selected_detections);
}

---

这是原作者的：

void draw_detections_v3(.....)
.....
qsort(selected_detections, selected_detections_num, sizeof(*selected_detections), compare_by_probs);
    int image_nut=0;//记录螺母数量 （在image.c的370行左右）
     int image_bolt=0;//记录螺栓数量
    for (i = 0; i < selected_detections_num; ++i) {
            int width = im.h * .002;
            if (width < 1)
                width = 1;
.....
            char nut[30];//*左上角第一行字符串  （430行左右）
             char bolt[30]; //*左上角第二行字符串
            if (im.c == 1) {
                draw_box_width_bw(im, left, top, right, bot, width, 0.8);    // 1 channel Black-White
            }
            else {
                draw_box_width(im, left, top, right, bot, width, red, green, blue); // 3 channels RGB
            }

....

int j;
                for (j = 0; j < classes; ++j) {
                    if (selected_detections[i].det.prob[j] > thresh && j != selected_detections[i].best_class) {
                        strcat(labelstr, ", ");
                        strcat(labelstr, names[j]);
                    }
                }
                char con[20]={0};//置信度添加  450行左右
        sprintf(con, "%.4f", selected_detections[i].det.prob[selected_detections[i].best_class]); 
        strcat(labelstr, ":");
        strcat(labelstr, con);//

        if(!strcmp(names[selected_detections[i].best_class], "nut"))//
        {  
            image_nut++;// 计数开始
            
        }
        else if(!strcmp(names[selected_detections[i].best_class], "bolt"))
        {
            image_bolt++;
            
        }
        //
                image label = get_label_v3(alphabet, labelstr, (im.h*.02));
                //draw_label(im, top + width, left, label, rgb);
                draw_weighted_label(im, top + width, left, label, rgb, 0.7);
....
if (selected_detections[i].det.mask) {
                image mask = float_to_image(14, 14, 1, selected_detections[i].det.mask);
                image resized_mask = resize_image(mask, b.w*im.w, b.h*im.h);
                image tmask = threshold_image(resized_mask, .5);
                embed_image(tmask, im, left, top);
                free_image(mask);
                free_image(resized_mask);
                free_image(tmask);
            }
    if (i==(selected_detections_num-1))//最终结果写入  484行左右
    {        sprintf(nut,"nut_num: %d",image_nut);
            
            sprintf(bolt,"bolt_num: %d",image_bolt);
    }
    
    image label_nut=get_label_v3(alphabet, nut, (im.h*.03));//last varible is size
    draw_weighted_label(im, 100, 150, label_nut, rgb); //显示函数
    free_image(label_nut);         
    image label_bolt=get_label_v3(alphabet, bolt, (im.h*.03));//last varible is size
    draw_weighted_label(im, 260, 150, label_bolt, rgb);
    free_image(label_bolt);     //
    }
    

    free(selected_detections);
}

参考：https://www.cnblogs.com/pine-apple/p/13213898.html