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525 lines
26 KiB
525 lines
26 KiB
--- |
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comments: true |
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description: Get started with YOLOv8 Predict mode and input sources. Accepts various input sources such as images, videos, and directories. |
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keywords: YOLOv8, predict mode, generator, streaming mode, input sources, video formats, arguments customization |
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--- |
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<img width="1024" src="https://github.com/ultralytics/assets/raw/main/yolov8/banner-integrations.png"> |
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YOLOv8 **predict mode** can generate predictions for various tasks, returning either a list of `Results` objects or a |
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memory-efficient generator of `Results` objects when using the streaming mode. Enable streaming mode by |
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passing `stream=True` in the predictor's call method. |
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!!! example "Predict" |
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=== "Return a list with `stream=False`" |
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```python |
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from ultralytics import YOLO |
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# Load a model |
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model = YOLO('yolov8n.pt') # pretrained YOLOv8n model |
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# Run batched inference on a list of images |
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results = model(['im1.jpg', 'im2.jpg']) # return a list of Results objects |
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# Process results list |
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for result in results: |
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boxes = result.boxes # Boxes object for bbox outputs |
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masks = result.masks # Masks object for segmentation masks outputs |
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keypoints = result.keypoints # Keypoints object for pose outputs |
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probs = result.probs # Class probabilities for classification outputs |
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``` |
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=== "Return a generator with `stream=True`" |
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```python |
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from ultralytics import YOLO |
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# Load a model |
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model = YOLO('yolov8n.pt') # pretrained YOLOv8n model |
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# Run batched inference on a list of images |
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results = model(['im1.jpg', 'im2.jpg'], stream=True) # return a generator of Results objects |
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# Process results generator |
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for result in results: |
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boxes = result.boxes # Boxes object for bbox outputs |
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masks = result.masks # Masks object for segmentation masks outputs |
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keypoints = result.keypoints # Keypoints object for pose outputs |
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probs = result.probs # Class probabilities for classification outputs |
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``` |
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## Inference Sources |
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YOLOv8 can process different types of input sources for inference, as shown in the table below. The sources include static images, video streams, and various data formats. The table also indicates whether each source can be used in streaming mode with the argument `stream=True` ✅. Streaming mode is beneficial for processing videos or live streams as it creates a generator of results instead of loading all frames into memory. |
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!!! tip "Tip" |
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Use `stream=True` for processing long videos or large datasets to efficiently manage memory. When `stream=False`, the results for all frames or data points are stored in memory, which can quickly add up and cause out-of-memory errors for large inputs. In contrast, `stream=True` utilizes a generator, which only keeps the results of the current frame or data point in memory, significantly reducing memory consumption and preventing out-of-memory issues. |
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| Source | Argument | Type | Notes | |
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|-------------|--------------------------------------------|---------------------------------------|----------------------------------------------------------------------------| |
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| image | `'image.jpg'` | `str` or `Path` | Single image file. | |
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| URL | `'https://ultralytics.com/images/bus.jpg'` | `str` | URL to an image. | |
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| screenshot | `'screen'` | `str` | Capture a screenshot. | |
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| PIL | `Image.open('im.jpg')` | `PIL.Image` | HWC format with RGB channels. | |
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| OpenCV | `cv2.imread('im.jpg')` | `np.ndarray` of `uint8 (0-255)` | HWC format with BGR channels. | |
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| numpy | `np.zeros((640,1280,3))` | `np.ndarray` of `uint8 (0-255)` | HWC format with BGR channels. | |
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| torch | `torch.zeros(16,3,320,640)` | `torch.Tensor` of `float32 (0.0-1.0)` | BCHW format with RGB channels. | |
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| CSV | `'sources.csv'` | `str` or `Path` | CSV file containing paths to images, videos, or directories. | |
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| video ✅ | `'video.mp4'` | `str` or `Path` | Video file in formats like MP4, AVI, etc. | |
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| directory ✅ | `'path/'` | `str` or `Path` | Path to a directory containing images or videos. | |
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| glob ✅ | `'path/*.jpg'` | `str` | Glob pattern to match multiple files. Use the `*` character as a wildcard. | |
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| YouTube ✅ | `'https://youtu.be/Zgi9g1ksQHc'` | `str` | URL to a YouTube video. | |
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| stream ✅ | `'rtsp://example.com/media.mp4'` | `str` | URL for streaming protocols such as RTSP, RTMP, or an IP address. | |
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Below are code examples for using each source type: |
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!!! example "Prediction sources" |
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=== "image" |
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Run inference on an image file. |
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```python |
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from ultralytics import YOLO |
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# Load a pretrained YOLOv8n model |
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model = YOLO('yolov8n.pt') |
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# Define path to the image file |
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source = 'path/to/image.jpg' |
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# Run inference on the source |
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results = model(source) # list of Results objects |
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``` |
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=== "screenshot" |
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Run inference on the current screen content as a screenshot. |
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```python |
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from ultralytics import YOLO |
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# Load a pretrained YOLOv8n model |
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model = YOLO('yolov8n.pt') |
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# Define current screenshot as source |
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source = 'screen' |
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# Run inference on the source |
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results = model(source) # list of Results objects |
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``` |
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=== "URL" |
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Run inference on an image or video hosted remotely via URL. |
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```python |
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from ultralytics import YOLO |
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# Load a pretrained YOLOv8n model |
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model = YOLO('yolov8n.pt') |
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# Define remote image or video URL |
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source = 'https://ultralytics.com/images/bus.jpg' |
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# Run inference on the source |
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results = model(source) # list of Results objects |
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``` |
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=== "PIL" |
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Run inference on an image opened with Python Imaging Library (PIL). |
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```python |
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from PIL import Image |
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from ultralytics import YOLO |
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# Load a pretrained YOLOv8n model |
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model = YOLO('yolov8n.pt') |
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# Open an image using PIL |
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source = Image.open('path/to/image.jpg') |
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# Run inference on the source |
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results = model(source) # list of Results objects |
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``` |
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=== "OpenCV" |
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Run inference on an image read with OpenCV. |
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```python |
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import cv2 |
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from ultralytics import YOLO |
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# Load a pretrained YOLOv8n model |
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model = YOLO('yolov8n.pt') |
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# Read an image using OpenCV |
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source = cv2.imread('path/to/image.jpg') |
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# Run inference on the source |
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results = model(source) # list of Results objects |
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``` |
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=== "numpy" |
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Run inference on an image represented as a numpy array. |
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```python |
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import numpy as np |
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from ultralytics import YOLO |
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# Load a pretrained YOLOv8n model |
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model = YOLO('yolov8n.pt') |
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# Create a random numpy array of HWC shape (640, 640, 3) with values in range [0, 255] and type uint8 |
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source = np.random.randint(low=0, high=255, size=(640, 640, 3), dtype='uint8') |
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# Run inference on the source |
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results = model(source) # list of Results objects |
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``` |
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=== "torch" |
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Run inference on an image represented as a PyTorch tensor. |
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```python |
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import torch |
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from ultralytics import YOLO |
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# Load a pretrained YOLOv8n model |
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model = YOLO('yolov8n.pt') |
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# Create a random torch tensor of BCHW shape (1, 3, 640, 640) with values in range [0, 1] and type float32 |
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source = torch.rand(1, 3, 640, 640, dtype=torch.float32) |
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# Run inference on the source |
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results = model(source) # list of Results objects |
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``` |
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=== "CSV" |
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Run inference on a collection of images, URLs, videos and directories listed in a CSV file. |
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```python |
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import torch |
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from ultralytics import YOLO |
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# Load a pretrained YOLOv8n model |
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model = YOLO('yolov8n.pt') |
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# Define a path to a CSV file with images, URLs, videos and directories |
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source = 'path/to/file.csv' |
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# Run inference on the source |
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results = model(source) # list of Results objects |
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``` |
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=== "video" |
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Run inference on a video file. By using `stream=True`, you can create a generator of Results objects to reduce memory usage. |
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```python |
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from ultralytics import YOLO |
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# Load a pretrained YOLOv8n model |
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model = YOLO('yolov8n.pt') |
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# Define path to video file |
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source = 'path/to/video.mp4' |
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# Run inference on the source |
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results = model(source, stream=True) # generator of Results objects |
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``` |
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=== "directory" |
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Run inference on all images and videos in a directory. To also capture images and videos in subdirectories use a glob pattern, i.e. `path/to/dir/**/*`. |
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```python |
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from ultralytics import YOLO |
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# Load a pretrained YOLOv8n model |
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model = YOLO('yolov8n.pt') |
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# Define path to directory containing images and videos for inference |
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source = 'path/to/dir' |
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# Run inference on the source |
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results = model(source, stream=True) # generator of Results objects |
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``` |
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=== "glob" |
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Run inference on all images and videos that match a glob expression with `*` characters. |
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```python |
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from ultralytics import YOLO |
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# Load a pretrained YOLOv8n model |
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model = YOLO('yolov8n.pt') |
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# Define a glob search for all JPG files in a directory |
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source = 'path/to/dir/*.jpg' |
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# OR define a recursive glob search for all JPG files including subdirectories |
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source = 'path/to/dir/**/*.jpg' |
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# Run inference on the source |
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results = model(source, stream=True) # generator of Results objects |
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``` |
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=== "YouTube" |
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Run inference on a YouTube video. By using `stream=True`, you can create a generator of Results objects to reduce memory usage for long videos. |
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```python |
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from ultralytics import YOLO |
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# Load a pretrained YOLOv8n model |
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model = YOLO('yolov8n.pt') |
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# Define source as YouTube video URL |
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source = 'https://youtu.be/Zgi9g1ksQHc' |
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# Run inference on the source |
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results = model(source, stream=True) # generator of Results objects |
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``` |
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=== "Stream" |
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Run inference on remote streaming sources using RTSP, RTMP, and IP address protocols. |
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```python |
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from ultralytics import YOLO |
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# Load a pretrained YOLOv8n model |
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model = YOLO('yolov8n.pt') |
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# Define source as RTSP, RTMP or IP streaming address |
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source = 'rtsp://example.com/media.mp4' |
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# Run inference on the source |
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results = model(source, stream=True) # generator of Results objects |
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``` |
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## Inference Arguments |
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`model.predict` accepts multiple arguments that control the prediction operation. These arguments can be passed directly to `model.predict`: |
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!!! example |
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```python |
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model.predict(source, save=True, imgsz=320, conf=0.5) |
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``` |
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All supported arguments: |
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| Key | Value | Description | |
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|----------------|------------------------|--------------------------------------------------------------------------------| |
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| `source` | `'ultralytics/assets'` | source directory for images or videos | |
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| `conf` | `0.25` | object confidence threshold for detection | |
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| `iou` | `0.7` | intersection over union (IoU) threshold for NMS | |
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| `half` | `False` | use half precision (FP16) | |
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| `device` | `None` | device to run on, i.e. cuda device=0/1/2/3 or device=cpu | |
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| `show` | `False` | show results if possible | |
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| `save` | `False` | save images with results | |
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| `save_txt` | `False` | save results as .txt file | |
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| `save_conf` | `False` | save results with confidence scores | |
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| `save_crop` | `False` | save cropped images with results | |
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| `hide_labels` | `False` | hide labels | |
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| `hide_conf` | `False` | hide confidence scores | |
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| `max_det` | `300` | maximum number of detections per image | |
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| `vid_stride` | `False` | video frame-rate stride | |
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| `line_width` | `None` | The line width of the bounding boxes. If None, it is scaled to the image size. | |
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| `visualize` | `False` | visualize model features | |
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| `augment` | `False` | apply image augmentation to prediction sources | |
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| `agnostic_nms` | `False` | class-agnostic NMS | |
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| `retina_masks` | `False` | use high-resolution segmentation masks | |
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| `classes` | `None` | filter results by class, i.e. class=0, or class=[0,2,3] | |
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| `boxes` | `True` | Show boxes in segmentation predictions | |
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## Image and Video Formats |
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YOLOv8 supports various image and video formats, as specified in [yolo/data/utils.py](https://github.com/ultralytics/ultralytics/blob/main/ultralytics/yolo/data/utils.py). See the tables below for the valid suffixes and example predict commands. |
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### Image Suffixes |
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The below table contains valid Ultralytics image formats. |
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| Image Suffixes | Example Predict Command | Reference | |
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|----------------|----------------------------------|-------------------------------------------------------------------------------| |
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| .bmp | `yolo predict source=image.bmp` | [Microsoft BMP File Format](https://en.wikipedia.org/wiki/BMP_file_format) | |
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| .dng | `yolo predict source=image.dng` | [Adobe DNG](https://www.adobe.com/products/photoshop/extend.displayTab2.html) | |
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| .jpeg | `yolo predict source=image.jpeg` | [JPEG](https://en.wikipedia.org/wiki/JPEG) | |
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| .jpg | `yolo predict source=image.jpg` | [JPEG](https://en.wikipedia.org/wiki/JPEG) | |
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| .mpo | `yolo predict source=image.mpo` | [Multi Picture Object](https://fileinfo.com/extension/mpo) | |
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| .png | `yolo predict source=image.png` | [Portable Network Graphics](https://en.wikipedia.org/wiki/PNG) | |
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| .tif | `yolo predict source=image.tif` | [Tag Image File Format](https://en.wikipedia.org/wiki/TIFF) | |
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| .tiff | `yolo predict source=image.tiff` | [Tag Image File Format](https://en.wikipedia.org/wiki/TIFF) | |
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| .webp | `yolo predict source=image.webp` | [WebP](https://en.wikipedia.org/wiki/WebP) | |
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| .pfm | `yolo predict source=image.pfm` | [Portable FloatMap](https://en.wikipedia.org/wiki/Netpbm#File_formats) | |
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### Video Suffixes |
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The below table contains valid Ultralytics video formats. |
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| Video Suffixes | Example Predict Command | Reference | |
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|----------------|----------------------------------|----------------------------------------------------------------------------------| |
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| .asf | `yolo predict source=video.asf` | [Advanced Systems Format](https://en.wikipedia.org/wiki/Advanced_Systems_Format) | |
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| .avi | `yolo predict source=video.avi` | [Audio Video Interleave](https://en.wikipedia.org/wiki/Audio_Video_Interleave) | |
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| .gif | `yolo predict source=video.gif` | [Graphics Interchange Format](https://en.wikipedia.org/wiki/GIF) | |
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| .m4v | `yolo predict source=video.m4v` | [MPEG-4 Part 14](https://en.wikipedia.org/wiki/M4V) | |
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| .mkv | `yolo predict source=video.mkv` | [Matroska](https://en.wikipedia.org/wiki/Matroska) | |
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| .mov | `yolo predict source=video.mov` | [QuickTime File Format](https://en.wikipedia.org/wiki/QuickTime_File_Format) | |
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| .mp4 | `yolo predict source=video.mp4` | [MPEG-4 Part 14 - Wikipedia](https://en.wikipedia.org/wiki/MPEG-4_Part_14) | |
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| .mpeg | `yolo predict source=video.mpeg` | [MPEG-1 Part 2](https://en.wikipedia.org/wiki/MPEG-1) | |
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| .mpg | `yolo predict source=video.mpg` | [MPEG-1 Part 2](https://en.wikipedia.org/wiki/MPEG-1) | |
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| .ts | `yolo predict source=video.ts` | [MPEG Transport Stream](https://en.wikipedia.org/wiki/MPEG_transport_stream) | |
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| .wmv | `yolo predict source=video.wmv` | [Windows Media Video](https://en.wikipedia.org/wiki/Windows_Media_Video) | |
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| .webm | `yolo predict source=video.webm` | [WebM Project](https://en.wikipedia.org/wiki/WebM) | |
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## Working with Results |
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The `Results` object contains the following components: |
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- `Results.boxes`: `Boxes` object with properties and methods for manipulating bounding boxes |
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- `Results.masks`: `Masks` object for indexing masks or getting segment coordinates |
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- `Results.keypoints`: `Keypoints` object for with properties and methods for manipulating predicted keypoints. |
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- `Results.probs`: `Probs` object for containing class probabilities. |
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- `Results.orig_img`: Original image loaded in memory |
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- `Results.path`: `Path` containing the path to the input image |
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Each result is composed of a `torch.Tensor` by default, which allows for easy manipulation: |
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!!! example "Results" |
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```python |
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results = results.cuda() |
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results = results.cpu() |
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results = results.to('cpu') |
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results = results.numpy() |
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``` |
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### Boxes |
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`Boxes` object can be used to index, manipulate, and convert bounding boxes to different formats. Box format conversion |
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operations are cached, meaning they're only calculated once per object, and those values are reused for future calls. |
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- Indexing a `Boxes` object returns a `Boxes` object: |
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!!! example "Boxes" |
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```python |
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results = model(img) |
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boxes = results[0].boxes |
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box = boxes[0] # returns one box |
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box.xyxy |
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``` |
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- Properties and conversions |
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!!! example "Boxes Properties" |
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```python |
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boxes.xyxy # box with xyxy format, (N, 4) |
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boxes.xywh # box with xywh format, (N, 4) |
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boxes.xyxyn # box with xyxy format but normalized, (N, 4) |
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boxes.xywhn # box with xywh format but normalized, (N, 4) |
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boxes.conf # confidence score, (N, ) |
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boxes.cls # cls, (N, ) |
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boxes.data # raw bboxes tensor, (N, 6) or boxes.boxes |
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``` |
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### Masks |
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`Masks` object can be used index, manipulate and convert masks to segments. The segment conversion operation is cached. |
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!!! example "Masks" |
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```python |
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results = model(inputs) |
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masks = results[0].masks # Masks object |
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masks.xy # x, y segments (pixels), List[segment] * N |
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masks.xyn # x, y segments (normalized), List[segment] * N |
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masks.data # raw masks tensor, (N, H, W) or masks.masks |
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``` |
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### Keypoints |
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`Keypoints` object can be used index, manipulate and normalize coordinates. The keypoint conversion operation is cached. |
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!!! example "Keypoints" |
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```python |
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results = model(inputs) |
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keypoints = results[0].keypoints # Masks object |
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keypoints.xy # x, y keypoints (pixels), (num_dets, num_kpts, 2/3), the last dimension can be 2 or 3, depends the model. |
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keypoints.xyn # x, y keypoints (normalized), (num_dets, num_kpts, 2/3) |
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keypoints.conf # confidence score(num_dets, num_kpts) of each keypoint if the last dimension is 3. |
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keypoints.data # raw keypoints tensor, (num_dets, num_kpts, 2/3) |
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``` |
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### probs |
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`Probs` object can be used index, get top1&top5 indices and scores of classification. |
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!!! example "Probs" |
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```python |
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results = model(inputs) |
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probs = results[0].probs # cls prob, (num_class, ) |
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probs.top5 # The top5 indices of classification, List[Int] * 5. |
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probs.top1 # The top1 indices of classification, a value with Int type. |
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probs.top5conf # The top5 scores of classification, a tensor with shape (5, ). |
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probs.top1conf # The top1 scores of classification. a value with torch.tensor type. |
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keypoints.data # raw probs tensor, (num_class, ) |
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``` |
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Class reference documentation for `Results` module and its components can be found [here](../reference/yolo/engine/results.md) |
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## Plotting results |
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You can use `plot()` function of `Result` object to plot results on in image object. It plots all components(boxes, |
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masks, classification probabilities, etc.) found in the results object |
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!!! example "Plotting" |
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```python |
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res = model(img) |
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res_plotted = res[0].plot() |
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cv2.imshow("result", res_plotted) |
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``` |
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| Argument | Description | |
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|-------------------------------|----------------------------------------------------------------------------------------| |
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| `conf (bool)` | Whether to plot the detection confidence score. | |
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| `line_width (int, optional)` | The line width of the bounding boxes. If None, it is scaled to the image size. | |
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| `font_size (float, optional)` | The font size of the text. If None, it is scaled to the image size. | |
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| `font (str)` | The font to use for the text. | |
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| `pil (bool)` | Whether to use PIL for image plotting. | |
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| `example (str)` | An example string to display. Useful for indicating the expected format of the output. | |
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| `img (numpy.ndarray)` | Plot to another image. if not, plot to original image. | |
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| `labels (bool)` | Whether to plot the label of bounding boxes. | |
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| `boxes (bool)` | Whether to plot the bounding boxes. | |
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| `masks (bool)` | Whether to plot the masks. | |
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| `probs (bool)` | Whether to plot classification probability. | |
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## Streaming Source `for`-loop |
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Here's a Python script using OpenCV (cv2) and YOLOv8 to run inference on video frames. This script assumes you have already installed the necessary packages (opencv-python and ultralytics). |
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!!! example "Streaming for-loop" |
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```python |
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import cv2 |
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from ultralytics import YOLO |
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# Load the YOLOv8 model |
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model = YOLO('yolov8n.pt') |
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# Open the video file |
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video_path = "path/to/your/video/file.mp4" |
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cap = cv2.VideoCapture(video_path) |
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# Loop through the video frames |
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while cap.isOpened(): |
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# Read a frame from the video |
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success, frame = cap.read() |
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if success: |
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# Run YOLOv8 inference on the frame |
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results = model(frame) |
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# Visualize the results on the frame |
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annotated_frame = results[0].plot() |
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# Display the annotated frame |
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cv2.imshow("YOLOv8 Inference", annotated_frame) |
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# Break the loop if 'q' is pressed |
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if cv2.waitKey(1) & 0xFF == ord("q"): |
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break |
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else: |
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# Break the loop if the end of the video is reached |
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break |
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# Release the video capture object and close the display window |
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cap.release() |
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cv2.destroyAllWindows() |
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``` |