目标检测系列之yolov5的detect.py代码详解
前言
哈喽呀！今天又是小白挑战读代码啊！所写的是目标检测系列之yolov5的detect.py代码详解。yolov5代码对应的是官网v6.1版本的，链接地址如下：https://github.com/ultralytics/yolov5
一、总体代码详解
废话不多说，直接上代码啦！
# YOLOv5 🚀 by Ultralytics, GPL-3.0 license
"""
Run inference on images, videos, directories, streams, etc.
Usage - sources:
$ python path/to/detect.py --weights yolov5s.pt --source 0 # webcam
img.jpg # image
vid.mp4 # video
path/ # directory
path/*.jpg # glob
'https://youtu.be/Zgi9g1ksQHc' # YouTube
'rtsp://example.com/media.mp4' # RTSP, RTMP, HTTP stream
Usage - formats:
$ python path/to/detect.py --weights yolov5s.pt # PyTorch
yolov5s.torchscript # TorchScript
yolov5s.onnx # ONNX Runtime or OpenCV DNN with --dnn
yolov5s.xml # OpenVINO
yolov5s.engine # TensorRT
yolov5s.mlmodel # CoreML (macOS-only)
yolov5s_saved_model # TensorFlow SavedModel
yolov5s.pb # TensorFlow GraphDef
yolov5s.tflite # TensorFlow Lite
yolov5s_edgetpu.tflite # TensorFlow Edge TPU
"""
import argparse
import os
import sys
from pathlib import Path
import torch
import torch.backends.cudnn as cudnn
FILE = Path(__file__).resolve() #绝对路径
ROOT = FILE.parents[0] # YOLOv5 root directory
if str(ROOT) not in sys.path: #模块查询路径的列表
sys.path.append(str(ROOT)) # add ROOT to PATH
ROOT = Path(os.path.relpath(ROOT, Path.cwd())) # relative 绝对路径转换为相对路径
from models.common import DetectMultiBackend
from utils.dataloaders import IMG_FORMATS, VID_FORMATS, LoadImages, LoadStreams
from utils.general import (LOGGER, check_file, check_img_size, check_imshow, check_requirements, colorstr, cv2,
increment_path, non_max_suppression, print_args, scale_coords, strip_optimizer, xyxy2xywh)
from utils.plots import Annotator, colors, save_one_box
from utils.torch_utils import select_device, time_sync
@torch.no_grad()
def run(
weights=ROOT / 'yolov5s.pt', # 权重文件地址 默认 weights/best.pt
source=ROOT / 'data/images', # 测试数据文件(图片或视频)的保存路径 默认data/images
data=ROOT / 'data/coco128.yaml', #数据存放在yaml文件中，包含了训练、验证，预测的路径
imgsz=(640, 640), # inference size (height, width) 输入图片的大小 默认640(pixels)
conf_thres=0.25, # object置信度阈值 默认0.25 用在nms中
iou_thres=0.45, # 做nms的iou阈值 默认0.45 用在nms中
max_det=1000, # 每张图片最多的目标数量 用在nms中
device='', # 设置代码执行的设备 cuda device, i.e. 0 or 0,1,2,3 or cpu
view_img=False, # 是否展示预测之后的图片或视频 默认False
save_txt=False, # 是否将预测的框坐标以txt文件格式保存 默认False
save_conf=False, # 是否保存预测每个目标的置信度到预测tx文件中 默认False
save_crop=False, # 是否需要将预测到的目标从原图中扣出来 剪切好 并保存 会在runs/detect/expn下生成crops文件，将剪切的图片保存在里面 默认False
nosave=False, # 是否不要保存预测后的图片 默认False 就是默认要保存预测后的图片
classes=None, # 在nms中是否是只保留某些特定的类 默认是None 就是所有类只要满足条件都可以保留
agnostic_nms=False, # 进行nms是否也除去不同类别之间的框 默认False
augment=False, # 预测是否也要采用数据增强 TTA 默认False
visualize=False, # visualize features
update=False, # 预测是否也要采用数据增强 TTA 默认False
project=ROOT / 'runs/detect', # 当前测试结果放在哪个主文件夹下 默认runs/detect
name='exp', # 当前测试结果放在run/detect下的文件名 默认是exp => run/detect/exp
exist_ok=False, # 是否存在当前文件 默认False 一般是 no exist-ok 连用 所以一般都要重新创建文件夹
line_thickness=3, # bounding box thickness (pixels) 画框的框框的线宽 默认是 3
hide_labels=False, # 画出的框框是否需要隐藏label信息 默认False
hide_conf=False, # 画出的框框是否需要隐藏conf信息 默认False
half=False, # 是否使用半精度 Float16 推理 可以缩短推理时间 但是默认是False
dnn=False, # use OpenCV DNN for ONNX inference 不使用
):
source = str(source)
save_img = not nosave and not source.endswith('.txt') # save inference images
# 是否保存预测后的图片 默认nosave=False 所以只要传入的文件地址不是以.txt结尾 就都是要保存预测后的图片的
is_file = Path(source).suffix[1:] in (IMG_FORMATS + VID_FORMATS) #判断suffix[1:]表示后缀是以jpg格式
is_url = source.lower().startswith(('rtsp://', 'rtmp://', 'http://', 'https://'))#判断地址是不是网络流地址
webcam = source.isnumeric() or source.endswith('.txt') or (is_url and not is_file)
# 是否是使用webcam 网页数据 一般是Fasle 因为我们一般是使用图片流LoadImages(可以处理图片/视频流文件)
if is_url and is_file:#如果是网络流地址，就会根据该地址去下载
source = check_file(source) # download
# Directories
save_dir = increment_path(Path(project) / name, exist_ok=exist_ok) # increment run
# 检查当前Path(project) / name是否存在 如果存在就新建新的save_dir 默认exist_ok=False 需要重建
# 将原先传入的名字扩展成新的save_dir 如runs/detect/exp存在 就扩展成 runs/detect/exp1
(save_dir / 'labels' if save_txt else save_dir).mkdir(parents=True, exist_ok=True) # make dir
# 如果需要save txt就新建save_dir / 'labels' 否则就新建save_dir
# 默认save_txt=False 所以这里一般都是新建一个 save_dir(runs/detect/expn)
# Load model
device = select_device(device) # 获取当前主机可用的设备
model = DetectMultiBackend(weights, device=device, dnn=dnn, data=data, fp16=half)#选择后端框架
stride, names, pt = model.stride, model.names, model.pt #读取值
imgsz = check_img_size(imgsz, s=stride) # check image size 这个尺寸得是32的倍数
# Dataloader
if webcam: #没有执行，所以去执行加载图片
view_img = check_imshow()
cudnn.benchmark = True # set True to speed up constant image size inference
dataset = LoadStreams(source, img_size=imgsz, stride=stride, auto=pt)
bs = len(dataset) # batch_size
else:
dataset = LoadImages(source, img_size=imgsz, stride=stride, auto=pt)
bs = 1 # batch_size 每次输入一张图片
vid_path, vid_writer = [None] * bs, [None] * bs
# Run inference 推理部分
model.warmup(imgsz=(1 if pt else bs, 3, *imgsz)) # warmup 传入一张图片，让GPU先热身一下
seen, windows, dt = 0, [], [0.0, 0.0, 0.0] #dt用来存储时间，seen是计数的功能
for path, im, im0s, vid_cap, s in dataset:
#去遍历图片，此时在dataloader中进行的是209到216部分，进行计数，
# 这里的path是指路径，im是指resize后的图片，im0是指原始图片，vid_cap=None，s是代表打印的信息
#以下部分是做预处理
t1 = time_sync()
im = torch.from_numpy(im).to(device) #torch.size=[3,640,480]
im = im.half() if model.fp16 else im.float() # uint8 to fp16/32
im /= 255 # 0 - 255 to 0.0 - 1.0 所有像素点除以255，是归一化的操作
if len(im.shape) == 3:
im = im[None] # expand for batch dim 缺少batch这个尺寸，所以将它扩充一下，变成[1，3,640,480]
t2 = time_sync()
dt[0] += t2 - t1
# Inference 做预测
visualize = increment_path(save_dir / Path(path).stem, mkdir=True) if visualize else False
pred = model(im, augment=augment, visualize=visualize) #模型预测出来的所有检测框，torch.size=[1,18900,85]
t3 = time_sync()
dt[1] += t3 - t2
# NMS非极大值抑制
# Apply NMS 进行NMS
# conf_thres: 置信度阈值
# iou_thres: iou阈值
# classes: 是否只保留特定的类别 默认为None
# agnostic_nms: 进行nms是否也去除不同类别之间的框
# max_det: 每张图片的最大目标个数 默认1000
# pred: [num_obj, 6] = [5, 6] 这里的预测信息pred还是相对于 img_size(640) 的
pred = non_max_suppression(pred, conf_thres, iou_thres, classes, agnostic_nms, max_det=max_det)
dt[2] += time_sync() - t3
# Second-stage classifier (optional)
# pred = utils.general.apply_classifier(pred, classifier_model, im, im0s)
# Process predictions 把所有的检测框画到原图中
for i, det in enumerate(pred): # per image i：每个batch的信息，det:表示5个检测框的信息
seen += 1 #seen是一个计数的功能
if webcam: # batch_size >= 1
p, im0, frame = path[i], im0s[i].copy(), dataset.count
s += f'{i}: '
else:
p, im0, frame = path, im0s.copy(), getattr(dataset, 'frame', 0)
p = Path(p) # to Path
save_path = str(save_dir / p.name) # im.jpg 存储路径+图片名
txt_path = str(save_dir / 'labels' / p.stem) + ('' if dataset.mode == 'image' else f'_{frame}') # im.txt默认不存
s += '%gx%g ' % im.shape[2:] #输出信息 图片shape (w, h)
gn = torch.tensor(im0.shape)[[1, 0, 1, 0]] # normalization gain whwh 获得原图的宽和高的大小
imc = im0.copy() if save_crop else im0 # for save_crop 是否要将检测的物体进行裁剪
annotator = Annotator(im0, line_width=line_thickness, example=str(names)) #定义绘图工具
if len(det): #判断有没有框
# Rescale boxes from img_size to im0 size
det[:, :4] = scale_coords(im.shape[2:], det[:, :4], im0.shape).round() #scale_coords坐标映射功能
# Print results
for c in det[:, -1].unique():
n = (det[:, -1] == c).sum() # detections per class
s += f"{n} {names[int(c)]}{'s' * (n > 1)}, " # add to string
# Write results
for *xyxy, conf, cls in reversed(det):
if save_txt: #默认是不执行的
xywh = (xyxy2xywh(torch.tensor(xyxy).view(1, 4)) / gn).view(-1).tolist() # normalized xywh
line = (cls, *xywh, conf) if save_conf else (cls, *xywh) # label format
with open(f'{txt_path}.txt', 'a') as f:
f.write(('%g ' * len(line)).rstrip() % line + '\n')
if save_img or save_crop or view_img: # Add bbox to image 执行这里
c = int(cls) # integer class
label = None if hide_labels else (names[c] if hide_conf else f'{names[c]} {conf:.2f}')
annotator.box_label(xyxy, label, color=colors(c, True))
if save_crop: #默认False，不执行
save_one_box(xyxy, imc, file=save_dir / 'crops' / names[c] / f'{p.stem}.jpg', BGR=True)
# Stream results
im0 = annotator.result() #返回画好的图片
if view_img:
if p not in windows:
windows.append(p)
cv2.namedWindow(str(p), cv2.WINDOW_NORMAL | cv2.WINDOW_KEEPRATIO) # allow window resize (Linux)
cv2.resizeWindow(str(p), im0.shape[1], im0.shape[0])
cv2.imshow(str(p), im0)
cv2.waitKey(1) # 1 millisecond
# Save results (image with detections)
if save_img:
if dataset.mode == 'image':
cv2.imwrite(save_path, im0)
else: # 'video' or 'stream'
if vid_path[i] != save_path: # new video
vid_path[i] = save_path
if isinstance(vid_writer[i], cv2.VideoWriter):
vid_writer[i].release() # release previous video writer
if vid_cap: # video
fps = vid_cap.get(cv2.CAP_PROP_FPS)
w = int(vid_cap.get(cv2.CAP_PROP_FRAME_WIDTH))
h = int(vid_cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
else: # stream
fps, w, h = 30, im0.shape[1], im0.shape[0]
save_path = str(Path(save_path).with_suffix('.mp4')) # force *.mp4 suffix on results videos
vid_writer[i] = cv2.VideoWriter(save_path, cv2.VideoWriter_fourcc(*'mp4v'), fps, (w, h))
vid_writer[i].write(im0)
# Print time (inference-only)
LOGGER.info(f'{s}Done. ({t3 - t2:.3f}s)')
# Print results 打印结果
t = tuple(x / seen * 1E3 for x in dt) # speeds per image
LOGGER.info(f'Speed: %.1fms pre-process, %.1fms inference, %.1fms NMS per image at shape {(1, 3, *imgsz)}' % t)
if save_txt or save_img:
s = f"\n{len(list(save_dir.glob('labels/*.txt')))} labels saved to {save_dir / 'labels'}" if save_txt else ''
LOGGER.info(f"Results saved to {colorstr('bold', save_dir)}{s}")
if update:
strip_optimizer(weights) # update model (to fix SourceChangeWarning)
def parse_opt():
parser = argparse.ArgumentParser()
parser.add_argument('--weights', nargs='+', type=str, default=ROOT / 'yolov5s.pt', help='model path(s)')
parser.add_argument('--source', type=str, default=ROOT / 'mydata/images/test', help='file/dir/URL/glob, 0 for webcam')
parser.add_argument('--data', type=str, default=ROOT / 'data/mydata.yaml', help='(optional) dataset.yaml path')
parser.add_argument('--imgsz', '--img', '--img-size', nargs='+', type=int, default=[640], help='inference size h,w')
parser.add_argument('--conf-thres', type=float, default=0.25, help='confidence threshold')
parser.add_argument('--iou-thres', type=float, default=0.45, help='NMS IoU threshold')
parser.add_argument('--max-det', type=int, default=1000, help='maximum detections per image')
parser.add_argument('--device', default='', help='cuda device, i.e. 0 or 0,1,2,3 or cpu')
parser.add_argument('--view-img', action='store_true', help='show results')
parser.add_argument('--save-txt', action='store_true', help='save results to *.txt')
parser.add_argument('--save-conf', action='store_true', help='save confidences in --save-txt labels')
parser.add_argument('--save-crop', action='store_true', help='save cropped prediction boxes')
parser.add_argument('--nosave', action='store_true', help='do not save images/videos')
parser.add_argument('--classes', nargs='+', type=int, help='filter by class: --classes 0, or --classes 0 2 3')
parser.add_argument('--agnostic-nms', action='store_true', help='class-agnostic NMS')
parser.add_argument('--augment', action='store_true', help='augmented inference')
parser.add_argument('--visualize', action='store_true', help='visualize features')
parser.add_argument('--update', action='store_true', help='update all models')
parser.add_argument('--project', default=ROOT / 'runs/detect', help='save results to project/name')
parser.add_argument('--name', default='exp', help='save results to project/name')
parser.add_argument('--exist-ok', action='store_true', help='existing project/name ok, do not increment')
parser.add_argument('--line-thickness', default=3, type=int, help='bounding box thickness (pixels)')
parser.add_argument('--hide-labels', default=False, action='store_true', help='hide labels')
parser.add_argument('--hide-conf', default=False, action='store_true', help='hide confidences')
parser.add_argument('--half', action='store_true', help='use FP16 half-precision inference')
parser.add_argument('--dnn', action='store_true', help='use OpenCV DNN for ONNX inference')
opt = parser.parse_args()
opt.imgsz *= 2 if len(opt.imgsz) == 1 else 1 # expand
print_args(vars(opt)) #打印参数信息
return opt
def main(opt):
check_requirements(exclude=('tensorboard', 'thop'))
run(**vars(opt))
if __name__ == "__main__":
opt = parse_opt()
main(opt)
二、代码逐步详解
1.开始入口
代码如下（示例）：
if __name__ == "__main__":2.接着执行
代码如下（示例）：在这里会进行一些参数的设置
opt = parse_opt()def parse_opt():
parser = argparse.ArgumentParser()
parser.add_argument('--weights', nargs='+', type=str, default=ROOT / 'yolov5s.pt', help='model path(s)')
parser.add_argument('--source', type=str, default=ROOT / 'mydata/images/test', help='file/dir/URL/glob, 0 for webcam')
parser.add_argument('--data', type=str, default=ROOT / 'data/mydata.yaml', help='(optional) dataset.yaml path')
parser.add_argument('--imgsz', '--img', '--img-size', nargs='+', type=int, default=[640], help='inference size h,w')
parser.add_argument('--conf-thres', type=float, default=0.25, help='confidence threshold')
parser.add_argument('--iou-thres', type=float, default=0.45, help='NMS IoU threshold')
parser.add_argument('--max-det', type=int, default=1000, help='maximum detections per image')
parser.add_argument('--device', default='', help='cuda device, i.e. 0 or 0,1,2,3 or cpu')
parser.add_argument('--view-img', action='store_true', help='show results')
parser.add_argument('--save-txt', action='store_true', help='save results to *.txt')
parser.add_argument('--save-conf', action='store_true', help='save confidences in --save-txt labels')
parser.add_argument('--save-crop', action='store_true', help='save cropped prediction boxes')
parser.add_argument('--nosave', action='store_true', help='do not save images/videos')
parser.add_argument('--classes', nargs='+', type=int, help='filter by class: --classes 0, or --classes 0 2 3')
parser.add_argument('--agnostic-nms', action='store_true', help='class-agnostic NMS')
parser.add_argument('--augment', action='store_true', help='augmented inference')
parser.add_argument('--visualize', action='store_true', help='visualize features')
parser.add_argument('--update', action='store_true', help='update all models')
parser.add_argument('--project', default=ROOT / 'runs/detect', help='save results to project/name')
parser.add_argument('--name', default='exp', help='save results to project/name')
parser.add_argument('--exist-ok', action='store_true', help='existing project/name ok, do not increment')
parser.add_argument('--line-thickness', default=3, type=int, help='bounding box thickness (pixels)')
parser.add_argument('--hide-labels', default=False, action='store_true', help='hide labels')
parser.add_argument('--hide-conf', default=False, action='store_true', help='hide confidences')
parser.add_argument('--half', action='store_true', help='use FP16 half-precision inference')
parser.add_argument('--dnn', action='store_true', help='use OpenCV DNN for ONNX inference')
opt = parser.parse_args()
opt.imgsz *= 2 if len(opt.imgsz) == 1 else 1 # expand
print_args(vars(opt)) #打印参数信息
return opt3.执行main函数
main(opt)def main(opt):
check_requirements(exclude=('tensorboard', 'thop'))
run(**vars(opt))def run(
weights=ROOT / 'yolov5s.pt', # 权重文件地址 默认 weights/best.pt
source=ROOT / 'data/images', # 测试数据文件(图片或视频)的保存路径 默认data/images
data=ROOT / 'data/coco128.yaml', #数据存放在yaml文件中，包含了训练、验证，预测的路径
imgsz=(640, 640), # inference size (height, width) 输入图片的大小 默认640(pixels)
conf_thres=0.25, # object置信度阈值 默认0.25 用在nms中
iou_thres=0.45, # 做nms的iou阈值 默认0.45 用在nms中
max_det=1000, # 每张图片最多的目标数量 用在nms中
device='', # 设置代码执行的设备 cuda device, i.e. 0 or 0,1,2,3 or cpu
view_img=False, # 是否展示预测之后的图片或视频 默认False
save_txt=False, # 是否将预测的框坐标以txt文件格式保存 默认False
save_conf=False, # 是否保存预测每个目标的置信度到预测tx文件中 默认False
save_crop=False, # 是否需要将预测到的目标从原图中扣出来 剪切好 并保存 会在runs/detect/expn下生成crops文件，将剪切的图片保存在里面 默认False
nosave=False, # 是否不要保存预测后的图片 默认False 就是默认要保存预测后的图片
classes=None, # 在nms中是否是只保留某些特定的类 默认是None 就是所有类只要满足条件都可以保留
agnostic_nms=False, # 进行nms是否也除去不同类别之间的框 默认False
augment=False, # 预测是否也要采用数据增强 TTA 默认False
visualize=False, # visualize features
update=False, # 预测是否也要采用数据增强 TTA 默认False
project=ROOT / 'runs/detect', # 当前测试结果放在哪个主文件夹下 默认runs/detect
name='exp', # 当前测试结果放在run/detect下的文件名 默认是exp => run/detect/exp
exist_ok=False, # 是否存在当前文件 默认False 一般是 no exist-ok 连用 所以一般都要重新创建文件夹
line_thickness=3, # bounding box thickness (pixels) 画框的框框的线宽 默认是 3
hide_labels=False, # 画出的框框是否需要隐藏label信息 默认False
hide_conf=False, # 画出的框框是否需要隐藏conf信息 默认False
half=False, # 是否使用半精度 Float16 推理 可以缩短推理时间 但是默认是False
dnn=False, # use OpenCV DNN for ONNX inference 不使用
):
source = str(source)
save_img = not nosave and not source.endswith('.txt') # save inference images
# 是否保存预测后的图片 默认nosave=False 所以只要传入的文件地址不是以.txt结尾 就都是要保存预测后的图片的
is_file = Path(source).suffix[1:] in (IMG_FORMATS + VID_FORMATS) #判断suffix[1:]表示后缀是以jpg格式
is_url = source.lower().startswith(('rtsp://', 'rtmp://', 'http://', 'https://'))#判断地址是不是网络流地址
webcam = source.isnumeric() or source.endswith('.txt') or (is_url and not is_file)
# 是否是使用webcam 网页数据 一般是Fasle 因为我们一般是使用图片流LoadImages(可以处理图片/视频流文件)
if is_url and is_file:#如果是网络流地址，就会根据该地址去下载
source = check_file(source) # download4.定义一些路径
save_dir = increment_path(Path(project) / name, exist_ok=exist_ok) # increment run
# 检查当前Path(project) / name是否存在 如果存在就新建新的save_dir 默认exist_ok=False 需要重建
# 将原先传入的名字扩展成新的save_dir 如runs/detect/exp存在 就扩展成 runs/detect/exp1
(save_dir / 'labels' if save_txt else save_dir).mkdir(parents=True, exist_ok=True) # make dir
# 如果需要save txt就新建save_dir / 'labels' 否则就新建save_dir
# 默认save_txt=False 所以这里一般都是新建一个 save_dir(runs/detect/expn)5.加载模型
device = select_device(device) # 获取当前主机可用的设备
model = DetectMultiBackend(weights, device=device, dnn=dnn, data=data, fp16=half)#选择后端框架
stride, names, pt = model.stride, model.names, model.pt #读取值
imgsz = check_img_size(imgsz, s=stride) # check image size 这个尺寸得是32的倍数这部分里面有个类DetecMultiBackend，就是一些检查设备的代码，个人觉得没有必要非要要看明白，具体代码如下：
class DetectMultiBackend(nn.Module):
# YOLOv5 MultiBackend class for python inference on various backends
def __init__(self, weights='yolov5s.pt', device=torch.device('cpu'), dnn=False, data=None, fp16=False):
# Usage:
# PyTorch: weights = *.pt
# TorchScript: *.torchscript
# ONNX Runtime: *.onnx
# ONNX OpenCV DNN: *.onnx with --dnn
# OpenVINO: *.xml
# CoreML: *.mlmodel
# TensorRT: *.engine
# TensorFlow SavedModel: *_saved_model
# TensorFlow GraphDef: *.pb
# TensorFlow Lite: *.tflite
# TensorFlow Edge TPU: *_edgetpu.tflite
from models.experimental import attempt_download, attempt_load # scoped to avoid circular import
super().__init__()
w = str(weights[0] if isinstance(weights, list) else weights) #yolov5s.pt
pt, jit, onnx, xml, engine, coreml, saved_model, pb, tflite, edgetpu, tfjs = self.model_type(w) # get backend
w = attempt_download(w) # 下载权重文件
fp16 &= (pt or jit or onnx or engine) and device.type != 'cpu' # FP16
stride, names = 32, [f'class{i}' for i in range(1000)] # assign defaults
if data: # assign class names (optional)
with open(data, errors='ignore') as f:
names = yaml.safe_load(f)['names']#加载data中的yaml文件中的name
if pt: # PyTorch
model = attempt_load(weights if isinstance(weights, list) else w, device=device)
stride = max(int(model.stride.max()), 32) # model stride
names = model.module.names if hasattr(model, 'module') else model.names # get class names
model.half() if fp16 else model.float()
self.model = model # explicitly assign for to(), cpu(), cuda(), half()
elif jit: # TorchScript
LOGGER.info(f'Loading {w} for TorchScript inference...')
extra_files = {'config.txt': ''} # model metadata
model = torch.jit.load(w, _extra_files=extra_files)
model.half() if fp16 else model.float()
if extra_files['config.txt']:
d = json.loads(extra_files['config.txt']) # extra_files dict
stride, names = int(d['stride']), d['names']
elif dnn: # ONNX OpenCV DNN
LOGGER.info(f'Loading {w} for ONNX OpenCV DNN inference...')
check_requirements(('opencv-python>=4.5.4',))
net = cv2.dnn.readNetFromONNX(w)
elif onnx: # ONNX Runtime
LOGGER.info(f'Loading {w} for ONNX Runtime inference...')
cuda = torch.cuda.is_available()
check_requirements(('onnx', 'onnxruntime-gpu' if cuda else 'onnxruntime'))
import onnxruntime
providers = ['CUDAExecutionProvider', 'CPUExecutionProvider'] if cuda else ['CPUExecutionProvider']
session = onnxruntime.InferenceSession(w, providers=providers)
meta = session.get_modelmeta().custom_metadata_map # metadata
if 'stride' in meta:
stride, names = int(meta['stride']), eval(meta['names'])
elif xml: # OpenVINO
LOGGER.info(f'Loading {w} for OpenVINO inference...')
check_requirements(('openvino',)) # requires openvino-dev: https://pypi.org/project/openvino-dev/
from openvino.runtime import Core, Layout, get_batch
ie = Core()
if not Path(w).is_file(): # if not *.xml
w = next(Path(w).glob('*.xml')) # get *.xml file from *_openvino_model dir
network = ie.read_model(model=w, weights=Path(w).with_suffix('.bin'))
if network.get_parameters()[0].get_layout().empty:
network.get_parameters()[0].set_layout(Layout("NCHW"))
batch_dim = get_batch(network)
if batch_dim.is_static:
batch_size = batch_dim.get_length()
executable_network = ie.compile_model(network, device_name="CPU") # device_name="MYRIAD" for Intel NCS2
output_layer = next(iter(executable_network.outputs))
meta = Path(w).with_suffix('.yaml')
if meta.exists():
stride, names = self._load_metadata(meta) # load metadata
elif engine: # TensorRT
LOGGER.info(f'Loading {w} for TensorRT inference...')
import tensorrt as trt # https://developer.nvidia.com/nvidia-tensorrt-download
check_version(trt.__version__, '7.0.0', hard=True) # require tensorrt>=7.0.0
Binding = namedtuple('Binding', ('name', 'dtype', 'shape', 'data', 'ptr'))
logger = trt.Logger(trt.Logger.INFO)
with open(w, 'rb') as f, trt.Runtime(logger) as runtime:
model = runtime.deserialize_cuda_engine(f.read())
bindings = OrderedDict()
fp16 = False # default updated below
for index in range(model.num_bindings):
name = model.get_binding_name(index)
dtype = trt.nptype(model.get_binding_dtype(index))
shape = tuple(model.get_binding_shape(index))
data = torch.from_numpy(np.empty(shape, dtype=np.dtype(dtype))).to(device)
bindings[name] = Binding(name, dtype, shape, data, int(data.data_ptr()))
if model.binding_is_input(index) and dtype == np.float16:
fp16 = True
binding_addrs = OrderedDict((n, d.ptr) for n, d in bindings.items())
context = model.create_execution_context()
batch_size = bindings['images'].shape[0]
elif coreml: # CoreML
LOGGER.info(f'Loading {w} for CoreML inference...')
import coremltools as ct
model = ct.models.MLModel(w)
else: # TensorFlow (SavedModel, GraphDef, Lite, Edge TPU)
if saved_model: # SavedModel
LOGGER.info(f'Loading {w} for TensorFlow SavedModel inference...')
import tensorflow as tf
keras = False # assume TF1 saved_model
model = tf.keras.models.load_model(w) if keras else tf.saved_model.load(w)
elif pb: # GraphDef https://www.tensorflow.org/guide/migrate#a_graphpb_or_graphpbtxt
LOGGER.info(f'Loading {w} for TensorFlow GraphDef inference...')
import tensorflow as tf
def wrap_frozen_graph(gd, inputs, outputs):
x = tf.compat.v1.wrap_function(lambda: tf.compat.v1.import_graph_def(gd, name=""), []) # wrapped
ge = x.graph.as_graph_element
return x.prune(tf.nest.map_structure(ge, inputs), tf.nest.map_structure(ge, outputs))
gd = tf.Graph().as_graph_def() # graph_def
with open(w, 'rb') as f:
gd.ParseFromString(f.read())
frozen_func = wrap_frozen_graph(gd, inputs="x:0", outputs="Identity:0")
elif tflite or edgetpu: # https://www.tensorflow.org/lite/guide/python#install_tensorflow_lite_for_python
try: # https://coral.ai/docs/edgetpu/tflite-python/#update-existing-tf-lite-code-for-the-edge-tpu
from tflite_runtime.interpreter import Interpreter, load_delegate
except ImportError:
import tensorflow as tf
Interpreter, load_delegate = tf.lite.Interpreter, tf.lite.experimental.load_delegate,
if edgetpu: # Edge TPU https://coral.ai/software/#edgetpu-runtime
LOGGER.info(f'Loading {w} for TensorFlow Lite Edge TPU inference...')
delegate = {
'Linux': 'libedgetpu.so.1',
'Darwin': 'libedgetpu.1.dylib',
'Windows': 'edgetpu.dll'}[platform.system()]
interpreter = Interpreter(model_path=w, experimental_delegates=[load_delegate(delegate)])
else: # Lite
LOGGER.info(f'Loading {w} for TensorFlow Lite inference...')
interpreter = Interpreter(model_path=w) # load TFLite model
interpreter.allocate_tensors() # allocate
input_details = interpreter.get_input_details() # inputs
output_details = interpreter.get_output_details() # outputs
elif tfjs:
raise Exception('ERROR: YOLOv5 TF.js inference is not supported')
else:
raise Exception(f'ERROR: {w} is not a supported format')
self.__dict__.update(locals()) # assign all variables to self
6.数据加载
if webcam: #没有执行，所以去执行加载图片
view_img = check_imshow()
cudnn.benchmark = True # set True to speed up constant image size inference
dataset = LoadStreams(source, img_size=imgsz, stride=stride, auto=pt)
bs = len(dataset) # batch_size
else:
dataset = LoadImages(source, img_size=imgsz, stride=stride, auto=pt)
bs = 1 # batch_size 每次输入一张图片
vid_path, vid_writer = [None] * bs, [None] * bs7、进行推理
model.warmup(imgsz=(1 if pt else bs, 3, *imgsz)) # warmup 传入一张图片，让GPU先热身一下
seen, windows, dt = 0, [], [0.0, 0.0, 0.0] #dt用来存储时间，seen是计数的功能
for path, im, im0s, vid_cap, s in dataset:
#去遍历图片，此时在dataloader中进行的是209到216部分，进行计数，
# 这里的path是指路径，im是指resize后的图片，im0是指原始图片，vid_cap=None，s是代表打印的信息
#以下部分是做预处理
t1 = time_sync()
im = torch.from_numpy(im).to(device) #torch.size=[3,640,480]
im = im.half() if model.fp16 else im.float() # uint8 to fp16/32
im /= 255 # 0 - 255 to 0.0 - 1.0 所有像素点除以255，是归一化的操作
if len(im.shape) == 3:
im = im[None] # expand for batch dim 缺少batch这个尺寸，所以将它扩充一下，变成[1，3,640,480]
t2 = time_sync()
dt[0] += t2 - t1
# Inference 做预测
visualize = increment_path(save_dir / Path(path).stem, mkdir=True) if visualize else False
pred = model(im, augment=augment, visualize=visualize) #模型预测出来的所有检测框，torch.size=[1,18900,85]
t3 = time_sync()
dt[1] += t3 - t2
# NMS非极大值抑制
# Apply NMS 进行NMS
# conf_thres: 置信度阈值
# iou_thres: iou阈值
# classes: 是否只保留特定的类别 默认为None
# agnostic_nms: 进行nms是否也去除不同类别之间的框
# max_det: 每张图片的最大目标个数 默认1000
# pred: [num_obj, 6] = [5, 6] 这里的预测信息pred还是相对于 img_size(640) 的
pred = non_max_suppression(pred, conf_thres, iou_thres, classes, agnostic_nms, max_det=max_det)
dt[2] += time_sync() - t3
# Second-stage classifier (optional)
# pred = utils.general.apply_classifier(pred, classifier_model, im, im0s)
# Process predictions 把所有的检测框画到原图中
for i, det in enumerate(pred): # per image i：每个batch的信息，det:表示5个检测框的信息
seen += 1 #seen是一个计数的功能
if webcam: # batch_size >= 1
p, im0, frame = path[i], im0s[i].copy(), dataset.count
s += f'{i}: '
else:
p, im0, frame = path, im0s.copy(), getattr(dataset, 'frame', 0)
p = Path(p) # to Path
save_path = str(save_dir / p.name) # im.jpg 存储路径+图片名
txt_path = str(save_dir / 'labels' / p.stem) + ('' if dataset.mode == 'image' else f'_{frame}') # im.txt默认不存
s += '%gx%g ' % im.shape[2:] #输出信息 图片shape (w, h)
gn = torch.tensor(im0.shape)[[1, 0, 1, 0]] # normalization gain whwh 获得原图的宽和高的大小
imc = im0.copy() if save_crop else im0 # for save_crop 是否要将检测的物体进行裁剪
annotator = Annotator(im0, line_width=line_thickness, example=str(names)) #定义绘图工具
if len(det): #判断有没有框
# Rescale boxes from img_size to im0 size
det[:, :4] = scale_coords(im.shape[2:], det[:, :4], im0.shape).round() #scale_coords坐标映射功能
# Print results
for c in det[:, -1].unique():
n = (det[:, -1] == c).sum() # detections per class
s += f"{n} {names[int(c)]}{'s' * (n > 1)}, " # add to string
# Write results
for *xyxy, conf, cls in reversed(det):
if save_txt: #默认是不执行的
xywh = (xyxy2xywh(torch.tensor(xyxy).view(1, 4)) / gn).view(-1).tolist() # normalized xywh
line = (cls, *xywh, conf) if save_conf else (cls, *xywh) # label format
with open(f'{txt_path}.txt', 'a') as f:
f.write(('%g ' * len(line)).rstrip() % line + '\n')
if save_img or save_crop or view_img: # Add bbox to image 执行这里
c = int(cls) # integer class
label = None if hide_labels else (names[c] if hide_conf else f'{names[c]} {conf:.2f}')
annotator.box_label(xyxy, label, color=colors(c, True))
if save_crop: #默认False，不执行
save_one_box(xyxy, imc, file=save_dir / 'crops' / names[c] / f'{p.stem}.jpg', BGR=True)
# Stream results
im0 = annotator.result() #返回画好的图片
if view_img:
if p not in windows:
windows.append(p)
cv2.namedWindow(str(p), cv2.WINDOW_NORMAL | cv2.WINDOW_KEEPRATIO) # allow window resize (Linux)
cv2.resizeWindow(str(p), im0.shape[1], im0.shape[0])
cv2.imshow(str(p), im0)
cv2.waitKey(1) # 1 millisecond
# Save results (image with detections)
if save_img:
if dataset.mode == 'image':
cv2.imwrite(save_path, im0)
else: # 'video' or 'stream'
if vid_path[i] != save_path: # new video
vid_path[i] = save_path
if isinstance(vid_writer[i], cv2.VideoWriter):
vid_writer[i].release() # release previous video writer
if vid_cap: # video
fps = vid_cap.get(cv2.CAP_PROP_FPS)
w = int(vid_cap.get(cv2.CAP_PROP_FRAME_WIDTH))
h = int(vid_cap.get(cv2.CAP_PROP_FRAME_HEIGHT))
else: # stream
fps, w, h = 30, im0.shape[1], im0.shape[0]
save_path = str(Path(save_path).with_suffix('.mp4')) # force *.mp4 suffix on results videos
vid_writer[i] = cv2.VideoWriter(save_path, cv2.VideoWriter_fourcc(*'mp4v'), fps, (w, h))
vid_writer[i].write(im0)
# Print time (inference-only)
LOGGER.info(f'{s}Done. ({t3 - t2:.3f}s)')8.打印结果
# Print results 打印结果
t = tuple(x / seen * 1E3 for x in dt) # speeds per image
LOGGER.info(f'Speed: %.1fms pre-process, %.1fms inference, %.1fms NMS per image at shape {(1, 3, *imgsz)}' % t)
if save_txt or save_img:
s = f"\n{len(list(save_dir.glob('labels/*.txt')))} labels saved to {save_dir / 'labels'}" if save_txt else ''
LOGGER.info(f"Results saved to {colorstr('bold', save_dir)}{s}")
if update:
strip_optimizer(weights) # update model (to fix SourceChangeWarning)总结
1、当遇到有些函数看不懂的时候，可以去百度，或者去CSDN搜索，多看，多听，慢慢的就懂了。
2、其次就是有些类具体如何调用的，可以按住Ctrl键，鼠标点击一下这个类名，跳进去看一下。
3、在调试的时候，有些东西看不明白，可以略过，因为只要主网络架构看明白就可以了，其余的重点的地方，可以之后自己慢慢看，慢慢消化。
4、如果是刚接触代码，比如像我一样的人，c语言学过，但不熟悉，python压根没碰过的，可以先尝试听听python的课，我看的是b站马士兵的课。但最重要的一点就是相信自己，只有不停的摸索，就会发现有些东西，自己不知不觉就学会了！
5、这些是我自己作为小白，刚接触计算机视觉的心得！以下参考内容推荐给大家！
花了2万多买的Python教程全套，现在分享给大家，入门到精通(Python全栈开发教程)_哔哩哔哩_bilibili
目标检测 YOLOv5 开源代码项目调试与讲解实战【土堆 x 布尔艺数】_哔哩哔哩_bilibili
推理部分之detect.py文件_哔哩哔哩_bilibili
强推！B站最适合新手入门的【YOLOv5目标检测】(原理+代码解析)课程，AI大佬手撕源码带你学！—人工智能/YOLO/图像识别_哔哩哔哩_bilibili文章来源：https://www.toymoban.com/news/detail-442656.html
【YOLOV5-5.x 源码解读】detect.py_满船清梦压星河HK的博客-CSDN博客_detect.py文章来源地址https://www.toymoban.com/news/detail-442656.html
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