Support CoreML NMS export for Segment, Pose and OBB (#19173)

Signed-off-by: Mohammed Yasin <32206511+Y-T-G@users.noreply.github.com>
Co-authored-by: UltralyticsAssistant <web@ultralytics.com>
Co-authored-by: Glenn Jocher <glenn.jocher@ultralytics.com>
Co-authored-by: Laughing <61612323+Laughing-q@users.noreply.github.com>

docs/en/macros/export-table.md

@@ -1,5 +1,4 @@
 {%set tip1 = ':material-information-outline:{ title="conf, iou, agnostic_nms are also available when nms=True" }' %}
-{%set tip2 = ':material-information-outline:{ title="conf, iou are also available when nms=True" }' %}
 
 | Format                                            | `format` Argument | Model                                           | Metadata | Arguments                                                                                     |
 | ------------------------------------------------- | ----------------- | ----------------------------------------------- | -------- | --------------------------------------------------------------------------------------------- |
@@ -8,7 +7,7 @@
 | [ONNX](../integrations/onnx.md)                   | `onnx`            | `{{ model_name or "yolo11n" }}.onnx`            | ✅       | `imgsz`, `half`, `dynamic`, `simplify`, `opset`, `nms`{{ tip1 }}, `batch`                     |
 | [OpenVINO](../integrations/openvino.md)           | `openvino`        | `{{ model_name or "yolo11n" }}_openvino_model/` | ✅       | `imgsz`, `half`, `dynamic`, `int8`, `nms`{{ tip1 }}, `batch`, `data`                          |
 | [TensorRT](../integrations/tensorrt.md)           | `engine`          | `{{ model_name or "yolo11n" }}.engine`          | ✅       | `imgsz`, `half`, `dynamic`, `simplify`, `workspace`, `int8`, `nms`{{ tip1 }}, `batch`, `data` |
-| [CoreML](../integrations/coreml.md)               | `coreml`          | `{{ model_name or "yolo11n" }}.mlpackage`       | ✅       | `imgsz`, `half`, `int8`, `nms`{{ tip2 }}, `batch`                                             |
+| [CoreML](../integrations/coreml.md)               | `coreml`          | `{{ model_name or "yolo11n" }}.mlpackage`       | ✅       | `imgsz`, `half`, `int8`, `nms`{{ tip1 }}, `batch`                                             |
 | [TF SavedModel](../integrations/tf-savedmodel.md) | `saved_model`     | `{{ model_name or "yolo11n" }}_saved_model/`    | ✅       | `imgsz`, `keras`, `int8`, `nms`{{ tip1 }}, `batch`                                            |
 | [TF GraphDef](../integrations/tf-graphdef.md)     | `pb`              | `{{ model_name or "yolo11n" }}.pb`              | ❌       | `imgsz`, `batch`                                                                              |
 | [TF Lite](../integrations/tflite.md)              | `tflite`          | `{{ model_name or "yolo11n" }}.tflite`          | ✅       | `imgsz`, `half`, `int8`, `nms`{{ tip1 }}, `batch`, `data`                                     |

docs/en/reference/engine/exporter.md

@@ -15,10 +15,6 @@ keywords: YOLOv8, export formats, ONNX, TensorRT, CoreML, machine learning model
 
 <br><br><hr><br>
 
-## ::: ultralytics.engine.exporter.IOSDetectModel
-
-<br><br><hr><br>
-
 ## ::: ultralytics.engine.exporter.NMSModel
 
 <br><br><hr><br>

tests/test_exports.py

@@ -116,14 +116,16 @@ def test_export_torchscript_matrix(task, dynamic, int8, half, batch, nms):
 @pytest.mark.skipif(not TORCH_1_9, reason="CoreML>=7.2 not supported with PyTorch<=1.8")
 @pytest.mark.skipif(checks.IS_PYTHON_3_12, reason="CoreML not supported in Python 3.12")
 @pytest.mark.parametrize(
-    "task, dynamic, int8, half, batch",
+    "task, dynamic, int8, half, batch, nms",
     [  # generate all combinations except for exclusion cases
-        (task, dynamic, int8, half, batch)
+        (task, dynamic, int8, half, batch, nms)
-        for task, dynamic, int8, half, batch in product(TASKS, [False], [True, False], [True, False], [1])
+        for task, dynamic, int8, half, batch, nms in product(
-        if not (int8 and half)
+            TASKS, [False], [True, False], [True, False], [1], [True, False]
+        )
+        if not ((int8 and half) or (task == "classify" and nms))
     ],
 )
-def test_export_coreml_matrix(task, dynamic, int8, half, batch):
+def test_export_coreml_matrix(task, dynamic, int8, half, batch, nms):
     """Test YOLO exports to CoreML format with various parameter configurations."""
     file = YOLO(TASK2MODEL[task]).export(
         format="coreml",
@@ -132,6 +134,7 @@ def test_export_coreml_matrix(task, dynamic, int8, half, batch):
         int8=int8,
         half=half,
         batch=batch,
+        nms=nms,
     )
     YOLO(file)([SOURCE] * batch, imgsz=32)  # exported model inference at batch=3
     shutil.rmtree(file)  # cleanup

ultralytics/engine/exporter.py

@@ -84,7 +84,6 @@ from ultralytics.utils import (
     LINUX,
     LOGGER,
     MACOS,
-    PYTHON_VERSION,
     RKNN_CHIPS,
     ROOT,
     WINDOWS,
@@ -356,7 +355,7 @@ class Exporter:
 
         y = None
         for _ in range(2):  # dry runs
-            y = NMSModel(model, self.args)(im) if self.args.nms and not coreml else model(im)
+            y = NMSModel(model, self.args)(im) if self.args.nms else model(im)
         if self.args.half and onnx and self.device.type != "cpu":
             im, model = im.half(), model.half()  # to FP16
 
@@ -766,12 +765,9 @@ class Exporter:
         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":
+        elif self.args.nms:
-            model = IOSDetectModel(self.model, self.im) if self.args.nms else self.model
+            model = NMSModel(self.model, self.args)
         else:
-            if self.args.nms:
-                LOGGER.warning(f"{prefix} WARNING ⚠️ 'nms=True' is only available for Detect models like 'yolo11n.pt'.")
-                # TODO CoreML Segment and Pose model pipelining
             model = self.model
 
         ts = torch.jit.trace(model.eval(), self.im, strict=False)  # TorchScript model
@@ -793,15 +789,6 @@ class Exporter:
                 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
-            else:
-                ct_model.save(str(f))  # save otherwise weights_dir does not exist
-                weights_dir = str(f / "Data/com.apple.CoreML/weights")
-            ct_model = self._pipeline_coreml(ct_model, weights_dir=weights_dir)
 
         m = self.metadata  # metadata dict
         ct_model.short_description = m.pop("description")
@@ -1391,112 +1378,6 @@ class Exporter:
         populator.populate()
         tmp_file.unlink()
 
-    def _pipeline_coreml(self, model, weights_dir=None, prefix=colorstr("CoreML Pipeline:")):
-        """YOLO CoreML pipeline."""
-        import coremltools as ct  # noqa
-
-        LOGGER.info(f"{prefix} starting pipeline with coremltools {ct.__version__}...")
-        _, _, h, w = list(self.im.shape)  # BCHW
-
-        # Output shapes
-        spec = model.get_spec()
-        out0, out1 = iter(spec.description.output)
-        if MACOS:
-            from PIL import Image
-
-            img = Image.new("RGB", (w, h))  # w=192, h=320
-            out = model.predict({"image": img})
-            out0_shape = out[out0.name].shape  # (3780, 80)
-            out1_shape = out[out1.name].shape  # (3780, 4)
-        else:  # linux and windows can not run model.predict(), get sizes from PyTorch model output y
-            out0_shape = self.output_shape[2], self.output_shape[1] - 4  # (3780, 80)
-            out1_shape = self.output_shape[2], 4  # (3780, 4)
-
-        # Checks
-        names = self.metadata["names"]
-        nx, ny = spec.description.input[0].type.imageType.width, spec.description.input[0].type.imageType.height
-        _, nc = out0_shape  # number of anchors, number of classes
-        assert len(names) == nc, f"{len(names)} names found for nc={nc}"  # check
-
-        # Define output shapes (missing)
-        out0.type.multiArrayType.shape[:] = out0_shape  # (3780, 80)
-        out1.type.multiArrayType.shape[:] = out1_shape  # (3780, 4)
-
-        # Model from spec
-        model = ct.models.MLModel(spec, weights_dir=weights_dir)
-
-        # 3. Create NMS protobuf
-        nms_spec = ct.proto.Model_pb2.Model()
-        nms_spec.specificationVersion = 5
-        for i in range(2):
-            decoder_output = model._spec.description.output[i].SerializeToString()
-            nms_spec.description.input.add()
-            nms_spec.description.input[i].ParseFromString(decoder_output)
-            nms_spec.description.output.add()
-            nms_spec.description.output[i].ParseFromString(decoder_output)
-
-        nms_spec.description.output[0].name = "confidence"
-        nms_spec.description.output[1].name = "coordinates"
-
-        output_sizes = [nc, 4]
-        for i in range(2):
-            ma_type = nms_spec.description.output[i].type.multiArrayType
-            ma_type.shapeRange.sizeRanges.add()
-            ma_type.shapeRange.sizeRanges[0].lowerBound = 0
-            ma_type.shapeRange.sizeRanges[0].upperBound = -1
-            ma_type.shapeRange.sizeRanges.add()
-            ma_type.shapeRange.sizeRanges[1].lowerBound = output_sizes[i]
-            ma_type.shapeRange.sizeRanges[1].upperBound = output_sizes[i]
-            del ma_type.shape[:]
-
-        nms = nms_spec.nonMaximumSuppression
-        nms.confidenceInputFeatureName = out0.name  # 1x507x80
-        nms.coordinatesInputFeatureName = out1.name  # 1x507x4
-        nms.confidenceOutputFeatureName = "confidence"
-        nms.coordinatesOutputFeatureName = "coordinates"
-        nms.iouThresholdInputFeatureName = "iouThreshold"
-        nms.confidenceThresholdInputFeatureName = "confidenceThreshold"
-        nms.iouThreshold = self.args.iou
-        nms.confidenceThreshold = self.args.conf
-        nms.pickTop.perClass = True
-        nms.stringClassLabels.vector.extend(names.values())
-        nms_model = ct.models.MLModel(nms_spec)
-
-        # 4. Pipeline models together
-        pipeline = ct.models.pipeline.Pipeline(
-            input_features=[
-                ("image", ct.models.datatypes.Array(3, ny, nx)),
-                ("iouThreshold", ct.models.datatypes.Double()),
-                ("confidenceThreshold", ct.models.datatypes.Double()),
-            ],
-            output_features=["confidence", "coordinates"],
-        )
-        pipeline.add_model(model)
-        pipeline.add_model(nms_model)
-
-        # Correct datatypes
-        pipeline.spec.description.input[0].ParseFromString(model._spec.description.input[0].SerializeToString())
-        pipeline.spec.description.output[0].ParseFromString(nms_model._spec.description.output[0].SerializeToString())
-        pipeline.spec.description.output[1].ParseFromString(nms_model._spec.description.output[1].SerializeToString())
-
-        # Update metadata
-        pipeline.spec.specificationVersion = 5
-        pipeline.spec.description.metadata.userDefined.update(
-            {"IoU threshold": str(nms.iouThreshold), "Confidence threshold": str(nms.confidenceThreshold)}
-        )
-
-        # Save the model
-        model = ct.models.MLModel(pipeline.spec, weights_dir=weights_dir)
-        model.input_description["image"] = "Input image"
-        model.input_description["iouThreshold"] = f"(optional) IoU threshold override (default: {nms.iouThreshold})"
-        model.input_description["confidenceThreshold"] = (
-            f"(optional) Confidence threshold override (default: {nms.confidenceThreshold})"
-        )
-        model.output_description["confidence"] = 'Boxes × Class confidence (see user-defined metadata "classes")'
-        model.output_description["coordinates"] = "Boxes × [x, y, width, height] (relative to image size)"
-        LOGGER.info(f"{prefix} pipeline success")
-        return model
-
     def add_callback(self, event: str, callback):
         """Appends the given callback."""
         self.callbacks[event].append(callback)
@@ -1507,26 +1388,6 @@ class Exporter:
             callback(self)
 
 
-class IOSDetectModel(torch.nn.Module):
-    """Wrap an Ultralytics YOLO model for Apple iOS CoreML export."""
-
-    def __init__(self, model, im):
-        """Initialize the IOSDetectModel class with a YOLO model and example image."""
-        super().__init__()
-        _, _, h, w = im.shape  # batch, channel, height, width
-        self.model = model
-        self.nc = len(model.names)  # number of classes
-        if w == h:
-            self.normalize = 1.0 / w  # scalar
-        else:
-            self.normalize = torch.tensor([1.0 / w, 1.0 / h, 1.0 / w, 1.0 / h])  # broadcast (slower, smaller)
-
-    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, self.nc), 1)
-        return cls, xywh * self.normalize  # confidence (3780, 80), coordinates (3780, 4)
-
-
 class NMSModel(torch.nn.Module):
     """Model wrapper with embedded NMS for Detect, Segment, Pose and OBB."""
 
@@ -1585,7 +1446,8 @@ class NMSModel(torch.nn.Module):
                 box = xywh2xyxy(box)
                 if self.is_tf:
                     # TFlite bug returns less boxes
-                    box = torch.nn.functional.pad(box, (0, 0, 0, mask.shape[0] - box.shape[0]))
+                    pad = torch.zeros((mask.shape[0] - box.shape[0], box.shape[-1]), device=box.device, dtype=box.dtype)
+                    box = torch.cat((box, pad))
             nmsbox = box.clone()
             # `8` is the minimum value experimented to get correct NMS results for obb
             multiplier = 8 if self.obb else 1
@@ -1622,6 +1484,6 @@ class NMSModel(torch.nn.Module):
                 [box[keep], score[keep].view(-1, 1), cls[keep].view(-1, 1).to(out.dtype), extra[keep]], dim=-1
             )
             # Zero-pad to max_det size to avoid reshape error
-            pad = (0, 0, 0, self.args.max_det - dets.shape[0])
+            pad = torch.zeros((self.args.max_det - dets.shape[0], out.shape[-1]), device=out.device, dtype=out.dtype)
-            out[i] = torch.nn.functional.pad(dets, pad)
+            out[i] = torch.cat((dets, pad))
         return (out, preds[1]) if self.model.task == "segment" else out

ultralytics/nn/autobackend.py

@@ -640,14 +640,10 @@ class AutoBackend(nn.Module):
             y = self.model.predict({"image": im_pil})  # coordinates are xywh normalized
             if "confidence" in y:
                 raise TypeError(
-                    "Ultralytics only supports inference of non-pipelined CoreML models exported with "
+                    "'model={w}' has an NMS pipeline created by an older version of Ultralytics. "
-                    f"'nms=False', but 'model={w}' has an NMS pipeline created by an 'nms=True' export."
+                    "CoreML inference with NMS is only supported for models exported with latest Ultralytics. "
+                    "You may export the model again with latest Ultralytics to resolve this."
                 )
-                # TODO: CoreML NMS inference handling
-                # from ultralytics.utils.ops import xywh2xyxy
-                # box = xywh2xyxy(y['coordinates'] * [[w, h, w, h]])  # xyxy pixels
-                # conf, cls = y['confidence'].max(1), y['confidence'].argmax(1).astype(np.float32)
-                # y = np.concatenate((box, conf.reshape(-1, 1), cls.reshape(-1, 1)), 1)
             y = list(y.values())
             if len(y) == 2 and len(y[1].shape) != 4:  # segmentation model
                 y = list(reversed(y))  # reversed for segmentation models (pred, proto)

ultralytics/utils/ops.py

@@ -441,12 +441,9 @@ def xywh2xyxy(x):
         y (np.ndarray | torch.Tensor): The bounding box coordinates in (x1, y1, x2, y2) format.
     """
     assert x.shape[-1] == 4, f"input shape last dimension expected 4 but input shape is {x.shape}"
-    y = empty_like(x)  # faster than clone/copy
     xy = x[..., :2]  # centers
     wh = x[..., 2:] / 2  # half width-height
-    y[..., :2] = xy - wh  # top left xy
+    return (np.concatenate if isinstance(x, np.ndarray) else torch.cat)((xy - wh, xy + wh), -1)
-    y[..., 2:] = xy + wh  # bottom right xy
-    return y
 
 
 def xywhn2xyxy(x, w=640, h=640, padw=0, padh=0):