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Object Detection

Object detection is a task that involves identifying the location and class of objects in an image or video stream.

The output of an object detector is a set of bounding boxes that enclose the objects in the image, along with class labels and confidence scores for each box. Object detection is a good choice when you need to identify objects of interest in a scene, but don't need to know exactly where the object is or its exact shape.



Watch: Object Detection with Pre-trained Ultralytics YOLOv8 Model.

Tip

YOLOv8 Detect models are the default YOLOv8 models, i.e. yolov8n.pt and are pretrained on COCO.

Models

YOLOv8 pretrained Detect models are shown here. Detect, Segment and Pose models are pretrained on the COCO dataset, while Classify models are pretrained on the ImageNet dataset.

Models download automatically from the latest Ultralytics release on first use.

Model size
(pixels)		 mAPval
50-95		 Speed
CPU ONNX
(ms)		 Speed
A100 TensorRT
(ms)		 params
(M)		 FLOPs
(B)
YOLOv8n 640 37.3 80.4 0.99 3.2 8.7
YOLOv8s 640 44.9 128.4 1.20 11.2 28.6
YOLOv8m 640 50.2 234.7 1.83 25.9 78.9
YOLOv8l 640 52.9 375.2 2.39 43.7 165.2
YOLOv8x 640 53.9 479.1 3.53 68.2 257.8
  • mAPval values are for single-model single-scale on COCO val2017 dataset.
    Reproduce by yolo val detect data=coco.yaml device=0
  • Speed averaged over COCO val images using an Amazon EC2 P4d instance.
    Reproduce by yolo val detect data=coco128.yaml batch=1 device=0|cpu

Train

Train YOLOv8n on the COCO128 dataset for 100 epochs at image size 640. For a full list of available arguments see the Configuration page.

from ultralytics import YOLO

# Load a model
model = YOLO('yolov8n.yaml')  # build a new model from YAML
model = YOLO('yolov8n.pt')  # load a pretrained model (recommended for training)
model = YOLO('yolov8n.yaml').load('yolov8n.pt')  # build from YAML and transfer weights

# Train the model
results = model.train(data='coco128.yaml', epochs=100, imgsz=640)

# Build a new model from YAML and start training from scratch
yolo detect train data=coco128.yaml model=yolov8n.yaml epochs=100 imgsz=640

# Start training from a pretrained *.pt model
yolo detect train data=coco128.yaml model=yolov8n.pt epochs=100 imgsz=640

# Build a new model from YAML, transfer pretrained weights to it and start training
yolo detect train data=coco128.yaml model=yolov8n.yaml pretrained=yolov8n.pt epochs=100 imgsz=640

Dataset format

YOLO detection dataset format can be found in detail in the Dataset Guide. To convert your existing dataset from other formats( like COCO etc.) to YOLO format, please use json2yolo tool by Ultralytics.

Val

Validate trained YOLOv8n model accuracy on the COCO128 dataset. No argument need to passed as the model retains it's training data and arguments as model attributes.

from ultralytics import YOLO

# Load a model
model = YOLO('yolov8n.pt')  # load an official model
model = YOLO('path/to/best.pt')  # load a custom model

# Validate the model
metrics = model.val()  # no arguments needed, dataset and settings remembered
metrics.box.map    # map50-95
metrics.box.map50  # map50
metrics.box.map75  # map75
metrics.box.maps   # a list contains map50-95 of each category

yolo detect val model=yolov8n.pt  # val official model
yolo detect val model=path/to/best.pt  # val custom model

Predict

Use a trained YOLOv8n model to run predictions on images.

from ultralytics import YOLO

# Load a model
model = YOLO('yolov8n.pt')  # load an official model
model = YOLO('path/to/best.pt')  # load a custom model

# Predict with the model
results = model('https://ultralytics.com/images/bus.jpg')  # predict on an image

yolo detect predict model=yolov8n.pt source='https://ultralytics.com/images/bus.jpg'  # predict with official model
yolo detect predict model=path/to/best.pt source='https://ultralytics.com/images/bus.jpg'  # predict with custom model

See full predict mode details in the Predict page.

Export

Export a YOLOv8n model to a different format like ONNX, CoreML, etc.

from ultralytics import YOLO

# Load a model
model = YOLO('yolov8n.pt')  # load an official model
model = YOLO('path/to/best.pt')  # load a custom trained

# Export the model
model.export(format='onnx')

yolo export model=yolov8n.pt format=onnx  # export official model
yolo export model=path/to/best.pt format=onnx  # export custom trained model

Available YOLOv8 export formats are in the table below. You can predict or validate directly on exported models, i.e. yolo predict model=yolov8n.onnx. Usage examples are shown for your model after export completes.

Format format Argument Model Metadata Arguments
PyTorch - yolov8n.pt ✅ -
TorchScript torchscript yolov8n.torchscript ✅ imgsz, optimize
ONNX onnx yolov8n.onnx ✅ imgsz, half, dynamic, simplify, opset
OpenVINO openvino yolov8n_openvino_model/ ✅ imgsz, half
TensorRT engine yolov8n.engine ✅ imgsz, half, dynamic, simplify, workspace
CoreML coreml yolov8n.mlpackage ✅ imgsz, half, int8, nms
TF SavedModel saved_model yolov8n_saved_model/ ✅ imgsz, keras
TF GraphDef pb yolov8n.pb ❌ imgsz
TF Lite tflite yolov8n.tflite ✅ imgsz, half, int8
TF Edge TPU edgetpu yolov8n_edgetpu.tflite ✅ imgsz
TF.js tfjs yolov8n_web_model/ ✅ imgsz
PaddlePaddle paddle yolov8n_paddle_model/ ✅ imgsz
ncnn ncnn yolov8n_ncnn_model/ ✅ imgsz, half

See full export details in the Export page.


Created 2023-03-12, Updated 2023-09-13
Authors: glenn-jocher (22), Laughing-q (1), sergiuwaxmann (1), AyushExel (1)

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