Add Fast Mobilenet-V2 Processor (#37113)

Co-authored-by: Yoni Gozlan <74535834+yonigozlan@users.noreply.github.com>

docs/source/en/model_doc/mobilenet_v2.md

@@ -84,6 +84,11 @@ If you're interested in submitting a resource to be included here, please feel f
 
 [[autodoc]] MobileNetV2ImageProcessor
     - preprocess
+
+## MobileNetV2ImageProcessorFast
+
+[[autodoc]] MobileNetV2ImageProcessorFast
+    - preprocess
     - post_process_semantic_segmentation
 
 ## MobileNetV2Model

src/transformers/models/auto/image_processing_auto.py

@@ -116,7 +116,7 @@ else:
             ("mistral3", ("PixtralImageProcessor", "PixtralImageProcessorFast")),
             ("mllama", ("MllamaImageProcessor",)),
             ("mobilenet_v1", ("MobileNetV1ImageProcessor",)),
-            ("mobilenet_v2", ("MobileNetV2ImageProcessor",)),
+            ("mobilenet_v2", ("MobileNetV2ImageProcessor", "MobileNetV2ImageProcessorFast")),
             ("mobilevit", ("MobileViTImageProcessor",)),
             ("mobilevitv2", ("MobileViTImageProcessor",)),
             ("nat", ("ViTImageProcessor", "ViTImageProcessorFast")),

src/transformers/models/mobilenet_v2/__init__.py

@@ -21,6 +21,7 @@ if TYPE_CHECKING:
     from .configuration_mobilenet_v2 import *
     from .feature_extraction_mobilenet_v2 import *
     from .image_processing_mobilenet_v2 import *
+    from .image_processing_mobilenet_v2_fast import *
     from .modeling_mobilenet_v2 import *
 else:
     import sys

src/transformers/models/mobilenet_v2/image_processing_mobilenet_v2_fast.py

@@ -0,0 +1,89 @@
+# coding=utf-8
+# Copyright 2025 The HuggingFace Inc. team. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Fast Image processor class for MobileNetV2."""
+
+from typing import List, Tuple
+
+from ...image_processing_utils_fast import BASE_IMAGE_PROCESSOR_FAST_DOCSTRING, BaseImageProcessorFast
+from ...image_utils import IMAGENET_STANDARD_MEAN, IMAGENET_STANDARD_STD, PILImageResampling
+from ...utils import add_start_docstrings, is_torch_available, is_torch_tensor
+
+
+if is_torch_available():
+    import torch
+
+
+@add_start_docstrings(
+    "Constructs a fast MobileNetV2 image processor.",
+    BASE_IMAGE_PROCESSOR_FAST_DOCSTRING,
+)
+class MobileNetV2ImageProcessorFast(BaseImageProcessorFast):
+    resample = PILImageResampling.BILINEAR
+    image_mean = IMAGENET_STANDARD_MEAN
+    image_std = IMAGENET_STANDARD_STD
+    size = {"shortest_edge": 256}
+    default_to_square = False
+    crop_size = {"height": 224, "width": 224}
+    do_resize = True
+    do_center_crop = True
+    do_rescale = True
+    do_normalize = True
+    do_convert_rgb = None
+
+    def post_process_semantic_segmentation(self, outputs, target_sizes: List[Tuple] = None):
+        """
+        Converts the output of [`MobileNetV2ForSemanticSegmentation`] into semantic segmentation maps. Only supports PyTorch.
+
+        Args:
+            outputs ([`MobileNetV2ForSemanticSegmentation`]):
+                Raw outputs of the model.
+            target_sizes (`List[Tuple]` of length `batch_size`, *optional*):
+                List of tuples corresponding to the requested final size (height, width) of each prediction. If unset,
+                predictions will not be resized.
+
+        Returns:
+            semantic_segmentation: `List[torch.Tensor]` of length `batch_size`, where each item is a semantic
+            segmentation map of shape (height, width) corresponding to the target_sizes entry (if `target_sizes` is
+            specified). Each entry of each `torch.Tensor` correspond to a semantic class id.
+        """
+        # TODO: add support for other frameworks
+        logits = outputs.logits
+
+        # Resize logits and compute semantic segmentation maps
+        if target_sizes is not None:
+            if len(logits) != len(target_sizes):
+                raise ValueError(
+                    "Make sure that you pass in as many target sizes as the batch dimension of the logits"
+                )
+
+            if is_torch_tensor(target_sizes):
+                target_sizes = target_sizes.numpy()
+
+            semantic_segmentation = []
+
+            for idx in range(len(logits)):
+                resized_logits = torch.nn.functional.interpolate(
+                    logits[idx].unsqueeze(dim=0), size=target_sizes[idx], mode="bilinear", align_corners=False
+                )
+                semantic_map = resized_logits[0].argmax(dim=0)
+                semantic_segmentation.append(semantic_map)
+        else:
+            semantic_segmentation = logits.argmax(dim=1)
+            semantic_segmentation = [semantic_segmentation[i] for i in range(semantic_segmentation.shape[0])]
+
+        return semantic_segmentation
+
+
+__all__ = ["MobileNetV2ImageProcessorFast"]

tests/models/mobilenet_v2/test_image_processing_mobilenet_v2.py

@@ -16,7 +16,7 @@
 import unittest
 
 from transformers.testing_utils import require_torch, require_vision
-from transformers.utils import is_vision_available
+from transformers.utils import is_torchvision_available, is_vision_available
 
 from ...test_image_processing_common import ImageProcessingTestMixin, prepare_image_inputs
 
@@ -24,6 +24,9 @@ from ...test_image_processing_common import ImageProcessingTestMixin, prepare_im
 if is_vision_available():
     from transformers import MobileNetV2ImageProcessor
 
+    if is_torchvision_available():
+        from transformers import MobileNetV2ImageProcessorFast
+
 
 class MobileNetV2ImageProcessingTester:
     def __init__(
@@ -79,6 +82,7 @@ class MobileNetV2ImageProcessingTester:
 @require_vision
 class MobileNetV2ImageProcessingTest(ImageProcessingTestMixin, unittest.TestCase):
     image_processing_class = MobileNetV2ImageProcessor if is_vision_available() else None
+    fast_image_processing_class = MobileNetV2ImageProcessorFast if is_torchvision_available() else None
 
     def setUp(self):
         super().setUp()
@@ -89,17 +93,19 @@ class MobileNetV2ImageProcessingTest(ImageProcessingTestMixin, unittest.TestCase
         return self.image_processor_tester.prepare_image_processor_dict()
 
     def test_image_processor_properties(self):
-        image_processor = self.image_processing_class(**self.image_processor_dict)
+        for image_processing_class in self.image_processor_list:
+            image_processor = image_processing_class(**self.image_processor_dict)
             self.assertTrue(hasattr(image_processor, "do_resize"))
             self.assertTrue(hasattr(image_processor, "size"))
             self.assertTrue(hasattr(image_processor, "do_center_crop"))
             self.assertTrue(hasattr(image_processor, "crop_size"))
 
     def test_image_processor_from_dict_with_kwargs(self):
-        image_processor = self.image_processing_class.from_dict(self.image_processor_dict)
+        for image_processing_class in self.image_processor_list:
+            image_processor = image_processing_class.from_dict(self.image_processor_dict)
             self.assertEqual(image_processor.size, {"shortest_edge": 20})
             self.assertEqual(image_processor.crop_size, {"height": 18, "width": 18})
 
-        image_processor = self.image_processing_class.from_dict(self.image_processor_dict, size=42, crop_size=84)
+            image_processor = image_processing_class.from_dict(self.image_processor_dict, size=42, crop_size=84)
             self.assertEqual(image_processor.size, {"shortest_edge": 42})
             self.assertEqual(image_processor.crop_size, {"height": 84, "width": 84})