Image Classification

Image classification is the simplest of the three tasks and involves classifying an entire image into one of a set of predefined classes.

The output of an image classifier is a single class label and a confidence score. Image classification is useful when you need to know only what class an image belongs to and don't need to know where objects of that class are located or what their exact shape is.

Watch: Explore Ultralytics YOLO Tasks: Image Classification using Ultralytics HUB

Models

YOLO11 pretrained Classify 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.

• acc values are model accuracies on the ImageNet dataset validation set.
  Reproduce by yolo val classify data=path/to/ImageNet device=0
• Speed averaged over ImageNet val images using an Amazon EC2 P4d instance.
  Reproduce by yolo val classify data=path/to/ImageNet batch=1 device=0|cpu

Train

Train YOLO11n-cls on the MNIST160 dataset for 100 epochs at image size 64. For a full list of available arguments see the Configuration page.

from ultralytics import YOLO

# Load a model
model = YOLO("yolo11n-cls.yaml")  # build a new model from YAML
model = YOLO("yolo11n-cls.pt")  # load a pretrained model (recommended for training)
model = YOLO("yolo11n-cls.yaml").load("yolo11n-cls.pt")  # build from YAML and transfer weights

# Train the model
results = model.train(data="mnist160", epochs=100, imgsz=64)

# Build a new model from YAML and start training from scratch
yolo classify train data=mnist160 model=yolo11n-cls.yaml epochs=100 imgsz=64

# Start training from a pretrained *.pt model
yolo classify train data=mnist160 model=yolo11n-cls.pt epochs=100 imgsz=64

# Build a new model from YAML, transfer pretrained weights to it and start training
yolo classify train data=mnist160 model=yolo11n-cls.yaml pretrained=yolo11n-cls.pt epochs=100 imgsz=64

Dataset format

YOLO classification dataset format can be found in detail in the Dataset Guide.

Val

Validate trained YOLO11n-cls model accuracy on the MNIST160 dataset. No arguments are needed as the model retains its training data and arguments as model attributes.

from ultralytics import YOLO

# Load a model
model = YOLO("yolo11n-cls.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.top1  # top1 accuracy
metrics.top5  # top5 accuracy

yolo classify val model=yolo11n-cls.pt  # val official model
yolo classify val model=path/to/best.pt  # val custom model

Predict

Use a trained YOLO11n-cls model to run predictions on images.

from ultralytics import YOLO

# Load a model
model = YOLO("yolo11n-cls.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 classify predict model=yolo11n-cls.pt source='https://ultralytics.com/images/bus.jpg'  # predict with official model
yolo classify 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 YOLO11n-cls model to a different format like ONNX, CoreML, etc.

from ultralytics import YOLO

# Load a model
model = YOLO("yolo11n-cls.pt")  # load an official model
model = YOLO("path/to/best.pt")  # load a custom trained model

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

yolo export model=yolo11n-cls.pt format=onnx  # export official model
yolo export model=path/to/best.pt format=onnx  # export custom trained model

Available YOLO11-cls export formats are in the table below. You can export to any format using the format argument, i.e. format='onnx' or format='engine'. You can predict or validate directly on exported models, i.e. yolo predict model=yolo11n-cls.onnx. Usage examples are shown for your model after export completes.

See full export details in the Export page.

FAQ

What is the purpose of YOLO11 in image classification?

YOLO11 models, such as yolo11n-cls.pt, are designed for efficient image classification. They assign a single class label to an entire image along with a confidence score. This is particularly useful for applications where knowing the specific class of an image is sufficient, rather than identifying the location or shape of objects within the image.

How do I train a YOLO11 model for image classification?

To train a YOLO11 model, you can use either Python or CLI commands. For example, to train a yolo11n-cls model on the MNIST160 dataset for 100 epochs at an image size of 64:

from ultralytics import YOLO

# Load a model
model = YOLO("yolo11n-cls.pt")  # load a pretrained model (recommended for training)

# Train the model
results = model.train(data="mnist160", epochs=100, imgsz=64)

yolo classify train data=mnist160 model=yolo11n-cls.pt epochs=100 imgsz=64

For more configuration options, visit the Configuration page.

Where can I find pretrained YOLO11 classification models?

Pretrained YOLO11 classification models can be found in the Models section. Models like yolo11n-cls.pt, yolo11s-cls.pt, yolo11m-cls.pt, etc., are pretrained on the ImageNet dataset and can be easily downloaded and used for various image classification tasks.

How can I export a trained YOLO11 model to different formats?

You can export a trained YOLO11 model to various formats using Python or CLI commands. For instance, to export a model to ONNX format:

from ultralytics import YOLO

# Load a model
model = YOLO("yolo11n-cls.pt")  # load the trained model

# Export the model to ONNX
model.export(format="onnx")

yolo export model=yolo11n-cls.pt format=onnx  # export the trained model to ONNX format

For detailed export options, refer to the Export page.

How do I validate a trained YOLO11 classification model?

To validate a trained model's accuracy on a dataset like MNIST160, you can use the following Python or CLI commands:

from ultralytics import YOLO

# Load a model
model = YOLO("yolo11n-cls.pt")  # load the trained model

# Validate the model
metrics = model.val()  # no arguments needed, uses the dataset and settings from training
metrics.top1  # top1 accuracy
metrics.top5  # top5 accuracy

yolo classify val model=yolo11n-cls.pt  # validate the trained model

For more information, visit the Validate section.

📅 Created 1 year ago ✏️ Updated 2 months ago

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