yolov8_test/docs/en/guides/object-cropping.md

comments	description	keywords
true	Learn how to isolate and extract specific objects from images and videos using YOLOv8 object cropping.	Ultralytics, YOLOv8, Object Detection, Object Cropping, Image Analysis, Video Processing, Data Extraction, Python

Object Cropping using Ultralytics YOLOv8 🚀

What is Object Cropping?

Object cropping with Ultralytics YOLOv8 involves isolating and extracting specific detected objects from an image or video. The YOLOv8 model capabilities are utilized to accurately identify and delineate objects, enabling precise cropping for further analysis or manipulation.

Advantages of Object Cropping?

• Focused Analysis: YOLOv8 facilitates targeted object cropping, allowing for in-depth examination or processing of individual items within a scene.
• Reduced Data Volume: By extracting only relevant objects, object cropping helps in minimizing data size, making it efficient for storage, transmission, or subsequent computational tasks.
• Enhanced Precision: YOLOv8's object detection accuracy ensures that the cropped objects maintain their spatial relationships, preserving the integrity of the visual information for detailed analysis.

!!! Example "Object Cropping using YOLOv8 Example"

=== "Object Cropping"
    ```python
    from ultralytics import YOLO
    from ultralytics.utils.plotting import Annotator, colors
    import cv2
    import os

    model = YOLO("yolov8n.pt")
    names = model.names

    cap = cv2.VideoCapture("path/to/video/file.mp4")
    assert cap.isOpened(), "Error reading video file"
    w, h, fps = (int(cap.get(x)) for x in (cv2.CAP_PROP_FRAME_WIDTH, cv2.CAP_PROP_FRAME_HEIGHT, cv2.CAP_PROP_FPS))

    crop_dir_name = "ultralytics_crop"
    if not os.path.exists(crop_dir_name):
        os.mkdir(crop_dir_name)

    # Video writer
    video_writer = cv2.VideoWriter("object_cropping_output.avi",
                                   cv2.VideoWriter_fourcc(*'mp4v'),
                                   fps, (w, h))

    idx = 0
    while cap.isOpened():
        success, im0 = cap.read()
        if not success:
            print("Video frame is empty or video processing has been successfully completed.")
            break

        results = model.predict(im0, show=False)
        boxes = results[0].boxes.xyxy.cpu().tolist()
        clss = results[0].boxes.cls.cpu().tolist()
        annotator = Annotator(im0, line_width=2, example=names)

        if boxes is not None:
            for box, cls in zip(boxes, clss):
                idx += 1
                annotator.box_label(box, color=colors(int(cls), True), label=names[int(cls)])

                crop_obj = im0[int(box[1]):int(box[3]), int(box[0]):int(box[2])]

                cv2.imwrite(os.path.join(crop_dir_name, str(idx)+".png"), crop_obj)

        cv2.imshow("ultralytics", im0)
        video_writer.write(im0)

        if cv2.waitKey(1) & 0xFF == ord('q'):
            break

    cap.release()
    video_writer.release()
    cv2.destroyAllWindows()
    ```

Arguments model.predict

Name	Type	Default	Description
source	str	'ultralytics/assets'	source directory for images or videos
conf	float	0.25	object confidence threshold for detection
iou	float	0.7	intersection over union (IoU) threshold for NMS
imgsz	int or tuple	640	image size as scalar or (h, w) list, i.e. (640, 480)
half	bool	False	use half precision (FP16)
device	None or str	None	device to run on, i.e. cuda device=0/1/2/3 or device=cpu
max_det	int	300	maximum number of detections per image
vid_stride	bool	False	video frame-rate stride
stream_buffer	bool	False	buffer all streaming frames (True) or return the most recent frame (False)
visualize	bool	False	visualize model features
augment	bool	False	apply image augmentation to prediction sources
agnostic_nms	bool	False	class-agnostic NMS
classes	list[int]	None	filter results by class, i.e. classes=0, or classes=[0,2,3]
retina_masks	bool	False	use high-resolution segmentation masks
embed	list[int]	None	return feature vectors/embeddings from given layers