Skip to content

Reference for ultralytics/engine/


This file is available at If you spot a problem please help fix it by contributing a Pull Request 🛠️. Thank you 🙏!


Exporter(cfg=DEFAULT_CFG, overrides=None, _callbacks=None)

A class for exporting a model.


Name Type Description
args SimpleNamespace

Configuration for the exporter.

callbacks list

List of callback functions. Defaults to None.


Name Type Description Default
cfg str

Path to a configuration file. Defaults to DEFAULT_CFG.

overrides dict

Configuration overrides. Defaults to None.

_callbacks dict

Dictionary of callback functions. Defaults to None.

Source code in ultralytics/engine/
def __init__(self, cfg=DEFAULT_CFG, overrides=None, _callbacks=None):
    Initializes the Exporter class.

        cfg (str, optional): Path to a configuration file. Defaults to DEFAULT_CFG.
        overrides (dict, optional): Configuration overrides. Defaults to None.
        _callbacks (dict, optional): Dictionary of callback functions. Defaults to None.
    self.args = get_cfg(cfg, overrides)
    if self.args.format.lower() in {"coreml", "mlmodel"}:  # fix attempt for protobuf<3.20.x errors
        os.environ["PROTOCOL_BUFFERS_PYTHON_IMPLEMENTATION"] = "python"  # must run before TensorBoard callback

    self.callbacks = _callbacks or callbacks.get_default_callbacks()


__call__(model=None) -> str

Returns list of exported files/dirs after running callbacks.

Source code in ultralytics/engine/
def __call__(self, model=None) -> str:
    """Returns list of exported files/dirs after running callbacks."""
    t = time.time()
    fmt = self.args.format.lower()  # to lowercase
    if fmt in {"tensorrt", "trt"}:  # 'engine' aliases
        fmt = "engine"
    if fmt in {"mlmodel", "mlpackage", "mlprogram", "apple", "ios", "coreml"}:  # 'coreml' aliases
        fmt = "coreml"
    fmts = tuple(export_formats()["Argument"][1:])  # available export formats
    flags = [x == fmt for x in fmts]
    if sum(flags) != 1:
        raise ValueError(f"Invalid export format='{fmt}'. Valid formats are {fmts}")
    jit, onnx, xml, engine, coreml, saved_model, pb, tflite, edgetpu, tfjs, paddle, ncnn = flags  # export booleans
    is_tf_format = any((saved_model, pb, tflite, edgetpu, tfjs))

    # Device
    if fmt == "engine" and self.args.device is None:
        LOGGER.warning("WARNING ⚠️ TensorRT requires GPU export, automatically assigning device=0")
        self.args.device = "0"
    self.device = select_device("cpu" if self.args.device is None else self.args.device)

    # Checks
    if not hasattr(model, "names"):
        model.names = default_class_names()
    model.names = check_class_names(model.names)
    if self.args.half and self.args.int8:
        LOGGER.warning("WARNING ⚠️ half=True and int8=True are mutually exclusive, setting half=False.")
        self.args.half = False
    if self.args.half and onnx and self.device.type == "cpu":
        LOGGER.warning("WARNING ⚠️ half=True only compatible with GPU export, i.e. use device=0")
        self.args.half = False
        assert not self.args.dynamic, "half=True not compatible with dynamic=True, i.e. use only one."
    self.imgsz = check_imgsz(self.args.imgsz, stride=model.stride, min_dim=2)  # check image size
    if self.args.int8 and (engine or xml):
        self.args.dynamic = True  # enforce dynamic to export TensorRT INT8; ensures ONNX is dynamic
    if self.args.optimize:
        assert not ncnn, "optimize=True not compatible with format='ncnn', i.e. use optimize=False"
        assert self.device.type == "cpu", "optimize=True not compatible with cuda devices, i.e. use device='cpu'"
    if edgetpu:
        if not LINUX:
            raise SystemError("Edge TPU export only supported on Linux. See")
        elif self.args.batch != 1:  # see
            LOGGER.warning("WARNING ⚠️ Edge TPU export requires batch size 1, setting batch=1.")
            self.args.batch = 1
    if isinstance(model, WorldModel):
            "WARNING ⚠️ YOLOWorld (original version) export is not supported to any format.\n"
            "WARNING ⚠️ YOLOWorldv2 models (i.e. '') only support export to "
            "(torchscript, onnx, openvino, engine, coreml) formats. "
            "See for details."
    if self.args.int8 and not = or TASK2DATA[getattr(model, "task", "detect")]  # assign default data
            "WARNING ⚠️ INT8 export requires a missing 'data' arg for calibration. "
            f"Using default 'data={}'."
    # Input
    im = torch.zeros(self.args.batch, 3, *self.imgsz).to(self.device)
    file = Path(
        getattr(model, "pt_path", None) or getattr(model, "yaml_file", None) or model.yaml.get("yaml_file", "")
    if file.suffix in {".yaml", ".yml"}:
        file = Path(

    # Update model
    model = deepcopy(model).to(self.device)
    for p in model.parameters():
        p.requires_grad = False
    model = model.fuse()
    for m in model.modules():
        if isinstance(m, (Detect, RTDETRDecoder)):  # includes all Detect subclasses like Segment, Pose, OBB
            m.dynamic = self.args.dynamic
            m.export = True
            m.format = self.args.format
        elif isinstance(m, C2f) and not is_tf_format:
            # EdgeTPU does not support FlexSplitV while split provides cleaner ONNX graph
            m.forward = m.forward_split

    y = None
    for _ in range(2):
        y = model(im)  # dry runs
    if self.args.half and onnx and self.device.type != "cpu":
        im, model = im.half(), model.half()  # to FP16

    # Filter warnings
    warnings.filterwarnings("ignore", category=torch.jit.TracerWarning)  # suppress TracerWarning
    warnings.filterwarnings("ignore", category=UserWarning)  # suppress shape prim::Constant missing ONNX warning
    warnings.filterwarnings("ignore", category=DeprecationWarning)  # suppress CoreML np.bool deprecation warning

    # Assign = im
    self.model = model
    self.file = file
    self.output_shape = (
        if isinstance(y, torch.Tensor)
        else tuple(tuple(x.shape if isinstance(x, torch.Tensor) else []) for x in y)
    self.pretty_name = Path(self.model.yaml.get("yaml_file", self.file)).stem.replace("yolo", "YOLO")
    data = model.args["data"] if hasattr(model, "args") and isinstance(model.args, dict) else ""
    description = f'Ultralytics {self.pretty_name} model {f"trained on {data}" if data else ""}'
    self.metadata = {
        "description": description,
        "author": "Ultralytics",
        "version": __version__,
        "license": "AGPL-3.0 License (",
        "docs": "",
        "stride": int(max(model.stride)),
        "task": model.task,
        "batch": self.args.batch,
        "imgsz": self.imgsz,
        "names": model.names,
    }  # model metadata
    if model.task == "pose":
        self.metadata["kpt_shape"] = model.model[-1].kpt_shape
        f"\n{colorstr('PyTorch:')} starting from '{file}' with input shape {tuple(im.shape)} BCHW and "
        f'output shape(s) {self.output_shape} ({file_size(file):.1f} MB)'

    # Exports
    f = [""] * len(fmts)  # exported filenames
    if jit or ncnn:  # TorchScript
        f[0], _ = self.export_torchscript()
    if engine:  # TensorRT required before ONNX
        f[1], _ = self.export_engine()
    if onnx:  # ONNX
        f[2], _ = self.export_onnx()
    if xml:  # OpenVINO
        f[3], _ = self.export_openvino()
    if coreml:  # CoreML
        f[4], _ = self.export_coreml()
    if is_tf_format:  # TensorFlow formats
        self.args.int8 |= edgetpu
        f[5], keras_model = self.export_saved_model()
        if pb or tfjs:  # pb prerequisite to tfjs
            f[6], _ = self.export_pb(keras_model=keras_model)
        if tflite:
            f[7], _ = self.export_tflite(keras_model=keras_model, nms=False, agnostic_nms=self.args.agnostic_nms)
        if edgetpu:
            f[8], _ = self.export_edgetpu(tflite_model=Path(f[5]) / f"{self.file.stem}_full_integer_quant.tflite")
        if tfjs:
            f[9], _ = self.export_tfjs()
    if paddle:  # PaddlePaddle
        f[10], _ = self.export_paddle()
    if ncnn:  # NCNN
        f[11], _ = self.export_ncnn()

    # Finish
    f = [str(x) for x in f if x]  # filter out '' and None
    if any(f):
        f = str(Path(f[-1]))
        square = self.imgsz[0] == self.imgsz[1]
        s = (
            if square
            else f"WARNING ⚠️ non-PyTorch val requires square images, 'imgsz={self.imgsz}' will not "
            f"work. Use export 'imgsz={max(self.imgsz)}' if val is required."
        imgsz = self.imgsz[0] if square else str(self.imgsz)[1:-1].replace(" ", "")
        predict_data = f"data={data}" if model.task == "segment" and fmt == "pb" else ""
        q = "int8" if self.args.int8 else "half" if self.args.half else ""  # quantization
            f'\nExport complete ({time.time() - t:.1f}s)'
            f"\nResults saved to {colorstr('bold', file.parent.resolve())}"
            f'\nPredict:         yolo predict task={model.task} model={f} imgsz={imgsz} {q} {predict_data}'
            f'\nValidate:        yolo val task={model.task} model={f} imgsz={imgsz} data={data} {q} {s}'

    return f  # return list of exported files/dirs


add_callback(event: str, callback)

Appends the given callback.

Source code in ultralytics/engine/
def add_callback(self, event: str, callback):
    """Appends the given callback."""



YOLOv8 CoreML export.

Source code in ultralytics/engine/
def export_coreml(self, prefix=colorstr("CoreML:")):
    """YOLOv8 CoreML export."""
    mlmodel = self.args.format.lower() == "mlmodel"  # legacy *.mlmodel export format requested
    check_requirements("coremltools>=6.0,<=6.2" if mlmodel else "coremltools>=7.0")
    import coremltools as ct  # noqa"\n{prefix} starting export with coremltools {ct.__version__}...")
    assert not WINDOWS, "CoreML export is not supported on Windows, please run on macOS or Linux."
    assert self.args.batch == 1, "CoreML batch sizes > 1 are not supported. Please retry at 'batch=1'."
    f = self.file.with_suffix(".mlmodel" if mlmodel else ".mlpackage")
    if f.is_dir():

    bias = [0.0, 0.0, 0.0]
    scale = 1 / 255
    classifier_config = None
    if self.model.task == "classify":
        classifier_config = ct.ClassifierConfig(list(self.model.names.values())) if self.args.nms else None
        model = self.model
    elif self.model.task == "detect":
        model = IOSDetectModel(self.model, if self.args.nms else self.model
        if self.args.nms:
            LOGGER.warning(f"{prefix} WARNING ⚠️ 'nms=True' is only available for Detect models like ''.")
            # TODO CoreML Segment and Pose model pipelining
        model = self.model

    ts = torch.jit.trace(model.eval(),, strict=False)  # TorchScript model
    ct_model = ct.convert(
        inputs=[ct.ImageType("image",, scale=scale, bias=bias)],
        convert_to="neuralnetwork" if mlmodel else "mlprogram",
    bits, mode = (8, "kmeans") if self.args.int8 else (16, "linear") if self.args.half else (32, None)
    if bits < 32:
        if "kmeans" in mode:
            check_requirements("scikit-learn")  # scikit-learn package required for k-means quantization
        if mlmodel:
            ct_model = ct.models.neural_network.quantization_utils.quantize_weights(ct_model, bits, mode)
        elif bits == 8:  # mlprogram already quantized to FP16
            import coremltools.optimize.coreml as cto

            op_config = cto.OpPalettizerConfig(mode="kmeans", nbits=bits, weight_threshold=512)
            config = cto.OptimizationConfig(global_config=op_config)
            ct_model = cto.palettize_weights(ct_model, config=config)
    if self.args.nms and self.model.task == "detect":
        if mlmodel:
            # coremltools<=6.2 NMS export requires Python<3.11
            check_version(PYTHON_VERSION, "<3.11", name="Python ", hard=True)
            weights_dir = None
    # save otherwise weights_dir does not exist
            weights_dir = str(f / "Data/")
        ct_model = self._pipeline_coreml(ct_model, weights_dir=weights_dir)

    m = self.metadata  # metadata dict
    ct_model.short_description = m.pop("description") = m.pop("author")
    ct_model.license = m.pop("license")
    ct_model.version = m.pop("version")
    ct_model.user_defined_metadata.update({k: str(v) for k, v in m.items()})
    try:  # save *.mlpackage
    except Exception as e:
            f"{prefix} WARNING ⚠️ CoreML export to *.mlpackage failed ({e}), reverting to *.mlmodel export. "
            f"Known coremltools Python 3.11 and Windows bugs"
        f = f.with_suffix(".mlmodel")
    return f, ct_model


export_edgetpu(tflite_model='', prefix=colorstr('Edge TPU:'))

YOLOv8 Edge TPU export

Source code in ultralytics/engine/
def export_edgetpu(self, tflite_model="", prefix=colorstr("Edge TPU:")):
    """YOLOv8 Edge TPU export"""
    LOGGER.warning(f"{prefix} WARNING ⚠️ Edge TPU known bug")

    cmd = "edgetpu_compiler --version"
    help_url = ""
    assert LINUX, f"export only supported on Linux. See {help_url}"
    if, stdout=subprocess.DEVNULL, stderr=subprocess.DEVNULL, shell=True).returncode != 0:"\n{prefix} export requires Edge TPU compiler. Attempting install from {help_url}")
        sudo ="sudo --version >/dev/null", shell=True).returncode == 0  # sudo installed on system
        for c in (
            "curl | sudo apt-key add -",
            'echo "deb coral-edgetpu-stable main" | '
            "sudo tee /etc/apt/sources.list.d/coral-edgetpu.list",
            "sudo apt-get update",
            "sudo apt-get install edgetpu-compiler",
   if sudo else c.replace("sudo ", ""), shell=True, check=True)
    ver =, shell=True, capture_output=True, check=True).stdout.decode().split()[-1]"\n{prefix} starting export with Edge TPU compiler {ver}...")
    f = str(tflite_model).replace(".tflite", "_edgetpu.tflite")  # Edge TPU model

    cmd = f'edgetpu_compiler -s -d -k 10 --out_dir "{Path(f).parent}" "{tflite_model}"'"{prefix} running '{cmd}'"), shell=True)
    return f, None



YOLOv8 TensorRT export

Source code in ultralytics/engine/
def export_engine(self, prefix=colorstr("TensorRT:")):
    """YOLOv8 TensorRT export"""
    assert != "cpu", "export running on CPU but must be on GPU, i.e. use 'device=0'"
    # self.args.simplify = True
    f_onnx, _ = self.export_onnx()  # run before TRT import

        import tensorrt as trt  # noqa
    except ImportError:
        if LINUX:
        import tensorrt as trt  # noqa
    check_version(trt.__version__, ">=7.0.0", hard=True)
    check_version(trt.__version__, "<=10.1.0", msg="")

    # Setup and checks"\n{prefix} starting export with TensorRT {trt.__version__}...")
    is_trt10 = int(trt.__version__.split(".")[0]) >= 10  # is TensorRT >= 10
    assert Path(f_onnx).exists(), f"failed to export ONNX file: {f_onnx}"
    f = self.file.with_suffix(".engine")  # TensorRT engine file
    logger = trt.Logger(trt.Logger.INFO)
    if self.args.verbose:
        logger.min_severity = trt.Logger.Severity.VERBOSE

    # Engine builder
    builder = trt.Builder(logger)
    config = builder.create_builder_config()
    workspace = int(self.args.workspace * (1 << 30))
    if is_trt10:
        config.set_memory_pool_limit(trt.MemoryPoolType.WORKSPACE, workspace)
    else:  # TensorRT versions 7, 8
        config.max_workspace_size = workspace
    flag = 1 << int(trt.NetworkDefinitionCreationFlag.EXPLICIT_BATCH)
    network = builder.create_network(flag)
    half = builder.platform_has_fast_fp16 and self.args.half
    int8 = builder.platform_has_fast_int8 and self.args.int8
    # Read ONNX file
    parser = trt.OnnxParser(network, logger)
    if not parser.parse_from_file(f_onnx):
        raise RuntimeError(f"failed to load ONNX file: {f_onnx}")

    # Network inputs
    inputs = [network.get_input(i) for i in range(network.num_inputs)]
    outputs = [network.get_output(i) for i in range(network.num_outputs)]
    for inp in inputs:'{prefix} input "{}" with shape{inp.shape} {inp.dtype}')
    for out in outputs:'{prefix} output "{}" with shape{out.shape} {out.dtype}')

    if self.args.dynamic:
        shape =
        if shape[0] <= 1:
            LOGGER.warning(f"{prefix} WARNING ⚠️ 'dynamic=True' model requires max batch size, i.e. 'batch=16'")
        profile = builder.create_optimization_profile()
        min_shape = (1, shape[1], 32, 32)  # minimum input shape
        max_shape = (*shape[:2], *(max(1, self.args.workspace) * d for d in shape[2:]))  # max input shape
        for inp in inputs:
            profile.set_shape(, min=min_shape, opt=shape, max=max_shape)
        config.add_optimization_profile(profile)"{prefix} building {'INT8' if int8 else 'FP' + ('16' if half else '32')} engine as {f}")
    if int8:
        config.profiling_verbosity = trt.ProfilingVerbosity.DETAILED

        class EngineCalibrator(trt.IInt8Calibrator):
            def __init__(
                dataset,  #
                batch: int,
                cache: str = "",
            ) -> None:
                self.dataset = dataset
                self.data_iter = iter(dataset)
                self.algo = trt.CalibrationAlgoType.ENTROPY_CALIBRATION_2
                self.batch = batch
                self.cache = Path(cache)

            def get_algorithm(self) -> trt.CalibrationAlgoType:
                """Get the calibration algorithm to use."""
                return self.algo

            def get_batch_size(self) -> int:
                """Get the batch size to use for calibration."""
                return self.batch or 1

            def get_batch(self, names) -> list:
                """Get the next batch to use for calibration, as a list of device memory pointers."""
                    im0s = next(self.data_iter)["img"] / 255.0
                    im0s ="cuda") if im0s.device.type == "cpu" else im0s
                    return [int(im0s.data_ptr())]
                except StopIteration:
                    # Return [] or None, signal to TensorRT there is no calibration data remaining
                    return None

            def read_calibration_cache(self) -> bytes:
                """Use existing cache instead of calibrating again, otherwise, implicitly return None."""
                if self.cache.exists() and self.cache.suffix == ".cache":
                    return self.cache.read_bytes()

            def write_calibration_cache(self, cache) -> None:
                """Write calibration cache to disk."""
                _ = self.cache.write_bytes(cache)

        # Load dataset w/ builder (for batching) and calibrate
        config.int8_calibrator = EngineCalibrator(
            batch=2 * self.args.batch,

    elif half:

    # Free CUDA memory
    del self.model

    # Write file
    build = builder.build_serialized_network if is_trt10 else builder.build_engine
    with build(network, config) as engine, open(f, "wb") as t:
        # Metadata
        meta = json.dumps(self.metadata)
        t.write(len(meta).to_bytes(4, byteorder="little", signed=True))
        # Model
        t.write(engine if is_trt10 else engine.serialize())

    return f, None



YOLOv8 NCNN export using PNNX

Source code in ultralytics/engine/
def export_ncnn(self, prefix=colorstr("NCNN:")):
    YOLOv8 NCNN export using PNNX
    import ncnn  # noqa"\n{prefix} starting export with NCNN {ncnn.__version__}...")
    f = Path(str(self.file).replace(self.file.suffix, f"_ncnn_model{os.sep}"))
    f_ts = self.file.with_suffix(".torchscript")

    name = Path("pnnx.exe" if WINDOWS else "pnnx")  # PNNX filename
    pnnx = name if name.is_file() else (ROOT / name)
    if not pnnx.is_file():
            f"{prefix} WARNING ⚠️ PNNX not found. Attempting to download binary file from "
            "\nNote PNNX Binary file must be placed in current working directory "
            f"or in {ROOT}. See PNNX repo for full installation instructions."
        system = "macos" if MACOS else "windows" if WINDOWS else "linux-aarch64" if ARM64 else "linux"
            release, assets = get_github_assets(repo="pnnx/pnnx")
            asset = [x for x in assets if f"{system}.zip" in x][0]
            assert isinstance(asset, str), "Unable to retrieve PNNX repo assets"  # i.e.
  "{prefix} successfully found latest PNNX asset file {asset}")
        except Exception as e:
            release = "20240410"
            asset = f"pnnx-{release}-{system}.zip"
            LOGGER.warning(f"{prefix} WARNING ⚠️ PNNX GitHub assets not found: {e}, using default {asset}")
        unzip_dir = safe_download(f"{release}/{asset}", delete=True)
        if check_is_path_safe(Path.cwd(), unzip_dir):  # avoid path traversal security vulnerability
            shutil.move(src=unzip_dir / name, dst=pnnx)  # move binary to ROOT
            pnnx.chmod(0o777)  # set read, write, and execute permissions for everyone
            shutil.rmtree(unzip_dir)  # delete unzip dir

    ncnn_args = [
        f'ncnnparam={f / "model.ncnn.param"}',
        f'ncnnbin={f / "model.ncnn.bin"}',
        f'ncnnpy={f / ""}',

    pnnx_args = [
        f'pnnxparam={f / "model.pnnx.param"}',
        f'pnnxbin={f / "model.pnnx.bin"}',
        f'pnnxpy={f / ""}',
        f'pnnxonnx={f / "model.pnnx.onnx"}',

    cmd = [
        f'inputshape="{[self.args.batch, 3, *self.imgsz]}"',
    f.mkdir(exist_ok=True)  # make ncnn_model directory"{prefix} running '{' '.join(cmd)}'"), check=True)

    # Remove debug files
    pnnx_files = [x.split("=")[-1] for x in pnnx_args]
    for f_debug in ("debug.bin", "debug.param", "debug2.bin", "debug2.param", *pnnx_files):

    yaml_save(f / "metadata.yaml", self.metadata)  # add metadata.yaml
    return str(f), None



YOLOv8 ONNX export.

Source code in ultralytics/engine/
def export_onnx(self, prefix=colorstr("ONNX:")):
    """YOLOv8 ONNX export."""
    requirements = ["onnx>=1.12.0"]
    if self.args.simplify:
        requirements += ["onnxslim>=0.1.31", "onnxruntime" + ("-gpu" if torch.cuda.is_available() else "")]
    import onnx  # noqa

    opset_version = self.args.opset or get_latest_opset()"\n{prefix} starting export with onnx {onnx.__version__} opset {opset_version}...")
    f = str(self.file.with_suffix(".onnx"))

    output_names = ["output0", "output1"] if isinstance(self.model, SegmentationModel) else ["output0"]
    dynamic = self.args.dynamic
    if dynamic:
        dynamic = {"images": {0: "batch", 2: "height", 3: "width"}}  # shape(1,3,640,640)
        if isinstance(self.model, SegmentationModel):
            dynamic["output0"] = {0: "batch", 2: "anchors"}  # shape(1, 116, 8400)
            dynamic["output1"] = {0: "batch", 2: "mask_height", 3: "mask_width"}  # shape(1,32,160,160)
        elif isinstance(self.model, DetectionModel):
            dynamic["output0"] = {0: "batch", 2: "anchors"}  # shape(1, 84, 8400)

        self.model.cpu() if dynamic else self.model,  # dynamic=True only compatible with cpu if dynamic else,
        do_constant_folding=True,  # WARNING: DNN inference with torch>=1.12 may require do_constant_folding=False
        dynamic_axes=dynamic or None,

    # Checks
    model_onnx = onnx.load(f)  # load onnx model
    # onnx.checker.check_model(model_onnx)  # check onnx model

    # Simplify
    if self.args.simplify:
            import onnxslim

  "{prefix} slimming with onnxslim {onnxslim.__version__}...")
            model_onnx = onnxslim.slim(model_onnx)

            # ONNX Simplifier (deprecated as must be compiled with 'cmake' in aarch64 and Conda CI environments)
            # import onnxsim
            # model_onnx, check = onnxsim.simplify(model_onnx)
            # assert check, "Simplified ONNX model could not be validated"
        except Exception as e:
            LOGGER.warning(f"{prefix} simplifier failure: {e}")

    # Metadata
    for k, v in self.metadata.items():
        meta = model_onnx.metadata_props.add()
        meta.key, meta.value = k, str(v), f)
    return f, model_onnx



YOLOv8 OpenVINO export.

Source code in ultralytics/engine/
def export_openvino(self, prefix=colorstr("OpenVINO:")):
    """YOLOv8 OpenVINO export."""
    check_requirements(f'openvino{"<=2024.0.0" if ARM64 else ">=2024.0.0"}')  # fix OpenVINO issue on ARM64
    import openvino as ov"\n{prefix} starting export with openvino {ov.__version__}...")
    assert TORCH_1_13, f"OpenVINO export requires torch>=1.13.0 but torch=={torch.__version__} is installed"
    ov_model = ov.convert_model(
        input=None if self.args.dynamic else [],,

    def serialize(ov_model, file):
        """Set RT info, serialize and save metadata YAML."""
        ov_model.set_rt_info("YOLOv8", ["model_info", "model_type"])
        ov_model.set_rt_info(True, ["model_info", "reverse_input_channels"])
        ov_model.set_rt_info(114, ["model_info", "pad_value"])
        ov_model.set_rt_info([255.0], ["model_info", "scale_values"])
        ov_model.set_rt_info(self.args.iou, ["model_info", "iou_threshold"])
        ov_model.set_rt_info([v.replace(" ", "_") for v in self.model.names.values()], ["model_info", "labels"])
        if self.model.task != "classify":
            ov_model.set_rt_info("fit_to_window_letterbox", ["model_info", "resize_type"])

        ov.runtime.save_model(ov_model, file, compress_to_fp16=self.args.half)
        yaml_save(Path(file).parent / "metadata.yaml", self.metadata)  # add metadata.yaml

    if self.args.int8:
        fq = str(self.file).replace(self.file.suffix, f"_int8_openvino_model{os.sep}")
        fq_ov = str(Path(fq) / self.file.with_suffix(".xml").name)
        import nncf

        def transform_fn(data_item) -> np.ndarray:
            """Quantization transform function."""
            data_item: torch.Tensor = data_item["img"] if isinstance(data_item, dict) else data_item
            assert data_item.dtype == torch.uint8, "Input image must be uint8 for the quantization preprocessing"
            im = data_item.numpy().astype(np.float32) / 255.0  # uint8 to fp16/32 and 0 - 255 to 0.0 - 1.0
            return np.expand_dims(im, 0) if im.ndim == 3 else im

        # Generate calibration data for integer quantization
        ignored_scope = None
        if isinstance(self.model.model[-1], Detect):
            # Includes all Detect subclasses like Segment, Pose, OBB, WorldDetect
            head_module_name = ".".join(list(self.model.named_modules())[-1][0].split(".")[:2])
            ignored_scope = nncf.IgnoredScope(  # ignore operations

        quantized_ov_model = nncf.quantize(
            calibration_dataset=nncf.Dataset(self.get_int8_calibration_dataloader(prefix), transform_fn),
        serialize(quantized_ov_model, fq_ov)
        return fq, None

    f = str(self.file).replace(self.file.suffix, f"_openvino_model{os.sep}")
    f_ov = str(Path(f) / self.file.with_suffix(".xml").name)

    serialize(ov_model, f_ov)
    return f, None



YOLOv8 Paddle export.

Source code in ultralytics/engine/
def export_paddle(self, prefix=colorstr("PaddlePaddle:")):
    """YOLOv8 Paddle export."""
    check_requirements(("paddlepaddle", "x2paddle"))
    import x2paddle  # noqa
    from x2paddle.convert import pytorch2paddle  # noqa"\n{prefix} starting export with X2Paddle {x2paddle.__version__}...")
    f = str(self.file).replace(self.file.suffix, f"_paddle_model{os.sep}")

    pytorch2paddle(module=self.model, save_dir=f, jit_type="trace", input_examples=[])  # export
    yaml_save(Path(f) / "metadata.yaml", self.metadata)  # add metadata.yaml
    return f, None


export_pb(keras_model, prefix=colorstr('TensorFlow GraphDef:'))

YOLOv8 TensorFlow GraphDef *.pb export

Source code in ultralytics/engine/
def export_pb(self, keras_model, prefix=colorstr("TensorFlow GraphDef:")):
    """YOLOv8 TensorFlow GraphDef *.pb export"""
    import tensorflow as tf  # noqa
    from tensorflow.python.framework.convert_to_constants import convert_variables_to_constants_v2  # noqa"\n{prefix} starting export with tensorflow {tf.__version__}...")
    f = self.file.with_suffix(".pb")

    m = tf.function(lambda x: keras_model(x))  # full model
    m = m.get_concrete_function(tf.TensorSpec(keras_model.inputs[0].shape, keras_model.inputs[0].dtype))
    frozen_func = convert_variables_to_constants_v2(m)
    frozen_func.graph.as_graph_def(), logdir=str(f.parent),, as_text=False)
    return f, None


export_saved_model(prefix=colorstr('TensorFlow SavedModel:'))

YOLOv8 TensorFlow SavedModel export.

Source code in ultralytics/engine/
def export_saved_model(self, prefix=colorstr("TensorFlow SavedModel:")):
    """YOLOv8 TensorFlow SavedModel export."""
    cuda = torch.cuda.is_available()
        import tensorflow as tf  # noqa
    except ImportError:
        suffix = "-macos" if MACOS else "-aarch64" if ARM64 else "" if cuda else "-cpu"
        version = ">=2.0.0"
        import tensorflow as tf  # noqa
            "keras",  # required by 'onnx2tf' package
            "tf_keras",  # required by 'onnx2tf' package
            "sng4onnx>=1.0.1",  # required by 'onnx2tf' package
            "onnx_graphsurgeon>=0.3.26",  # required by 'onnx2tf' package
            "tflite_support<=0.4.3" if IS_JETSON else "tflite_support",  # fix ImportError 'GLIBCXX_3.4.29'
            "flatbuffers>=23.5.26,<100",  # update old 'flatbuffers' included inside tensorflow package
            "onnxruntime-gpu" if cuda else "onnxruntime",
        cmds="--extra-index-url",  # onnx_graphsurgeon only on NVIDIA
    )"\n{prefix} starting export with tensorflow {tf.__version__}...")
    import onnx2tf

    f = Path(str(self.file).replace(self.file.suffix, "_saved_model"))
    if f.is_dir():
        shutil.rmtree(f)  # delete output folder

    # Pre-download calibration file to fix
    onnx2tf_file = Path("calibration_image_sample_data_20x128x128x3_float32.npy")
    if not onnx2tf_file.exists():
        attempt_download_asset(f"{onnx2tf_file}.zip", unzip=True, delete=True)

    # Export to ONNX
    self.args.simplify = True
    f_onnx, _ = self.export_onnx()

    # Export to TF
    np_data = None
    if self.args.int8:
        tmp_file = f / "tmp_tflite_int8_calibration_images.npy"  # int8 calibration images file
        verbosity = "info"
            images = [batch["img"].permute(0, 2, 3, 1) for batch in self.get_int8_calibration_dataloader(prefix)]
            images =, 0).float()
            # mean = images.view(-1, 3).mean(0)  # imagenet mean [123.675, 116.28, 103.53]
            # std = images.view(-1, 3).std(0)  # imagenet std [58.395, 57.12, 57.375]
  , images.numpy().astype(np.float32))  # BHWC
            np_data = [["images", tmp_file, [[[[0, 0, 0]]]], [[[[255, 255, 255]]]]]]
        verbosity = "error""{prefix} starting TFLite export with onnx2tf {onnx2tf.__version__}...")
        quant_type="per-tensor",  # "per-tensor" (faster) or "per-channel" (slower but more accurate)
    yaml_save(f / "metadata.yaml", self.metadata)  # add metadata.yaml

    # Remove/rename TFLite models
    if self.args.int8:
        for file in f.rglob("*_dynamic_range_quant.tflite"):
            file.rename(file.with_name(file.stem.replace("_dynamic_range_quant", "_int8") + file.suffix))
        for file in f.rglob("*_integer_quant_with_int16_act.tflite"):
            file.unlink()  # delete extra fp16 activation TFLite files

    # Add TFLite metadata
    for file in f.rglob("*.tflite"):
        f.unlink() if "quant_with_int16_act.tflite" in str(f) else self._add_tflite_metadata(file)

    return str(f), tf.saved_model.load(f, tags=None, options=None)  # load saved_model as Keras model



YOLOv8 TensorFlow.js export.

Source code in ultralytics/engine/
def export_tfjs(self, prefix=colorstr("TensorFlow.js:")):
    """YOLOv8 TensorFlow.js export."""
    if ARM64:
        # Fix error: `np.object` was a deprecated alias for the builtin `object` when exporting to TF.js on ARM64
    import tensorflow as tf
    import tensorflowjs as tfjs  # noqa"\n{prefix} starting export with tensorflowjs {tfjs.__version__}...")
    f = str(self.file).replace(self.file.suffix, "_web_model")  # js dir
    f_pb = str(self.file.with_suffix(".pb"))  # *.pb path

    gd = tf.Graph().as_graph_def()  # TF GraphDef
    with open(f_pb, "rb") as file:
    outputs = ",".join(gd_outputs(gd))"\n{prefix} output node names: {outputs}")

    quantization = "--quantize_float16" if self.args.half else "--quantize_uint8" if self.args.int8 else ""
    with spaces_in_path(f_pb) as fpb_, spaces_in_path(f) as f_:  # exporter can not handle spaces in path
        cmd = (
            "tensorflowjs_converter "
            f'--input_format=tf_frozen_model {quantization} --output_node_names={outputs} "{fpb_}" "{f_}"'
        )"{prefix} running '{cmd}'"), shell=True)

    if " " in f:
        LOGGER.warning(f"{prefix} WARNING ⚠️ your model may not work correctly with spaces in path '{f}'.")

    # f_json = Path(f) / 'model.json'  # *.json path
    # with open(f_json, 'w') as j:  # sort JSON Identity_* in ascending order
    #     subst = re.sub(
    #         r'{"outputs": {"Identity.?.?": {"name": "Identity.?.?"}, '
    #         r'"Identity.?.?": {"name": "Identity.?.?"}, '
    #         r'"Identity.?.?": {"name": "Identity.?.?"}, '
    #         r'"Identity.?.?": {"name": "Identity.?.?"}}}',
    #         r'{"outputs": {"Identity": {"name": "Identity"}, '
    #         r'"Identity_1": {"name": "Identity_1"}, '
    #         r'"Identity_2": {"name": "Identity_2"}, '
    #         r'"Identity_3": {"name": "Identity_3"}}}',
    #         f_json.read_text(),
    #     )
    #     j.write(subst)
    yaml_save(Path(f) / "metadata.yaml", self.metadata)  # add metadata.yaml
    return f, None


export_tflite(keras_model, nms, agnostic_nms, prefix=colorstr('TensorFlow Lite:'))

YOLOv8 TensorFlow Lite export.

Source code in ultralytics/engine/
def export_tflite(self, keras_model, nms, agnostic_nms, prefix=colorstr("TensorFlow Lite:")):
    """YOLOv8 TensorFlow Lite export."""
    # BUG
    import tensorflow as tf  # noqa"\n{prefix} starting export with tensorflow {tf.__version__}...")
    saved_model = Path(str(self.file).replace(self.file.suffix, "_saved_model"))
    if self.args.int8:
        f = saved_model / f"{self.file.stem}_int8.tflite"  # fp32 in/out
    elif self.args.half:
        f = saved_model / f"{self.file.stem}_float16.tflite"  # fp32 in/out
        f = saved_model / f"{self.file.stem}_float32.tflite"
    return str(f), None



YOLOv8 TorchScript model export.

Source code in ultralytics/engine/
def export_torchscript(self, prefix=colorstr("TorchScript:")):
    """YOLOv8 TorchScript model export.""""\n{prefix} starting export with torch {torch.__version__}...")
    f = self.file.with_suffix(".torchscript")

    ts = torch.jit.trace(self.model,, strict=False)
    extra_files = {"config.txt": json.dumps(self.metadata)}  # torch._C.ExtraFilesMap()
    if self.args.optimize:  #"{prefix} optimizing for mobile...")
        from torch.utils.mobile_optimizer import optimize_for_mobile

        optimize_for_mobile(ts)._save_for_lite_interpreter(str(f), _extra_files=extra_files)
    else:, _extra_files=extra_files)
    return f, None



Build and return a dataloader suitable for calibration of INT8 models.

Source code in ultralytics/engine/
def get_int8_calibration_dataloader(self, prefix=""):
    """Build and return a dataloader suitable for calibration of INT8 models.""""{prefix} collecting INT8 calibration images from 'data={}'")
    data = (check_cls_dataset if self.model.task == "classify" else check_det_dataset)(
    dataset = YOLODataset(
        data[self.args.split or "val"],
        batch_size=self.args.batch * 2,  # NOTE TensorRT INT8 calibration should use 2x batch size
    n = len(dataset)
    if n < 300:
        LOGGER.warning(f"{prefix} WARNING ⚠️ >300 images recommended for INT8 calibration, found {n} images.")
    return build_dataloader(dataset, batch=self.args.batch * 2, workers=0)  # required for batch loading


run_callbacks(event: str)

Execute all callbacks for a given event.

Source code in ultralytics/engine/
def run_callbacks(self, event: str):
    """Execute all callbacks for a given event."""
    for callback in self.callbacks.get(event, []):


IOSDetectModel(model, im)

Bases: Module

Wrap an Ultralytics YOLO model for Apple iOS CoreML export.

Source code in ultralytics/engine/
def __init__(self, model, im):
    """Initialize the IOSDetectModel class with a YOLO model and example image."""
    _, _, h, w = im.shape  # batch, channel, height, width
    self.model = model = len(model.names)  # number of classes
    if w == h:
        self.normalize = 1.0 / w  # scalar
        self.normalize = torch.tensor([1.0 / w, 1.0 / h, 1.0 / w, 1.0 / h])  # broadcast (slower, smaller)



Normalize predictions of object detection model with input size-dependent factors.

Source code in ultralytics/engine/
def forward(self, x):
    """Normalize predictions of object detection model with input size-dependent factors."""
    xywh, cls = self.model(x)[0].transpose(0, 1).split((4,, 1)
    return cls, xywh * self.normalize  # confidence (3780, 80), coordinates (3780, 4)



YOLOv8 export formats.

Source code in ultralytics/engine/
def export_formats():
    """YOLOv8 export formats."""
    import pandas  # scope for faster 'import ultralytics'

    x = [
        ["PyTorch", "-", ".pt", True, True],
        ["TorchScript", "torchscript", ".torchscript", True, True],
        ["ONNX", "onnx", ".onnx", True, True],
        ["OpenVINO", "openvino", "_openvino_model", True, False],
        ["TensorRT", "engine", ".engine", False, True],
        ["CoreML", "coreml", ".mlpackage", True, False],
        ["TensorFlow SavedModel", "saved_model", "_saved_model", True, True],
        ["TensorFlow GraphDef", "pb", ".pb", True, True],
        ["TensorFlow Lite", "tflite", ".tflite", True, False],
        ["TensorFlow Edge TPU", "edgetpu", "_edgetpu.tflite", True, False],
        ["TensorFlow.js", "tfjs", "_web_model", True, False],
        ["PaddlePaddle", "paddle", "_paddle_model", True, True],
        ["NCNN", "ncnn", "_ncnn_model", True, True],
    return pandas.DataFrame(x, columns=["Format", "Argument", "Suffix", "CPU", "GPU"])



TensorFlow GraphDef model output node names.

Source code in ultralytics/engine/
def gd_outputs(gd):
    """TensorFlow GraphDef model output node names."""
    name_list, input_list = [], []
    for node in gd.node:  # tensorflow.core.framework.node_def_pb2.NodeDef
    return sorted(f"{x}:0" for x in list(set(name_list) - set(input_list)) if not x.startswith("NoOp"))



YOLOv8 export decorator, i.e. @try_export.

Source code in ultralytics/engine/
def try_export(inner_func):
    """YOLOv8 export decorator, i.e. @try_export."""
    inner_args = get_default_args(inner_func)

    def outer_func(*args, **kwargs):
        """Export a model."""
        prefix = inner_args["prefix"]
            with Profile() as dt:
                f, model = inner_func(*args, **kwargs)
  "{prefix} export success ✅ {dt.t:.1f}s, saved as '{f}' ({file_size(f):.1f} MB)")
            return f, model
        except Exception as e:
  "{prefix} export failure ❌ {dt.t:.1f}s: {e}")
            raise e

    return outer_func

Created 2023-11-12, Updated 2024-07-21
Authors: glenn-jocher (6), Burhan-Q (1), Laughing-q (1)