Refactored and modified private api for resize functional op (#6191)

* Refactored and modified private api for resize functional op

* Fixed failures

* More updates

* Fixed flake8

test/test_transforms_tensor.py

@@ -394,9 +394,7 @@ class TestResize:
     @pytest.mark.parametrize(
         "size",
         [
-            [
-                32,
-            ],
+            [32],
             [32, 32],
             (32, 32),
             [34, 35],
@@ -412,7 +410,7 @@ class TestResize:
             # This is a trivial cast to float of uint8 data to test all cases
             tensor = tensor.to(dt)
         if max_size is not None and len(size) != 1:
-            pytest.xfail("with max_size, size must be a sequence with 2 elements")
+            pytest.skip("Size should be an int or a sequence of length 1 if max_size is specified")
 
         transform = T.Resize(size=size, interpolation=interpolation, max_size=max_size)
         s_transform = torch.jit.script(transform)
@@ -420,11 +418,7 @@ class TestResize:
         _test_transform_vs_scripted_on_batch(transform, s_transform, batch_tensors)
 
     def test_resize_save(self, tmpdir):
-        transform = T.Resize(
-            size=[
-                32,
-            ]
-        )
+        transform = T.Resize(size=[32])
         s_transform = torch.jit.script(transform)
         s_transform.save(os.path.join(tmpdir, "t_resize.pt"))
 
@@ -435,12 +429,8 @@ class TestResize:
         "size",
         [
             (32,),
-            [
-                44,
-            ],
-            [
-                32,
-            ],
+            [44],
+            [32],
             [32, 32],
             (32, 32),
             [44, 55],

torchvision/prototype/transforms/functional/_geometry.py

@@ -42,6 +42,8 @@ def resize_image_tensor(
     max_size: Optional[int] = None,
     antialias: Optional[bool] = None,
 ) -> torch.Tensor:
+    # TODO: use _compute_output_size to enable max_size option
+    max_size  # ununsed right now
     new_height, new_width = size
     num_channels, old_height, old_width = get_dimensions_image_tensor(image)
     batch_shape = image.shape[:-3]
@@ -49,7 +51,6 @@ def resize_image_tensor(
         image.reshape((-1, num_channels, old_height, old_width)),
         size=size,
         interpolation=interpolation.value,
-        max_size=max_size,
         antialias=antialias,
     ).reshape(batch_shape + (num_channels, new_height, new_width))
 
@@ -60,7 +61,9 @@ def resize_image_pil(
     interpolation: InterpolationMode = InterpolationMode.BILINEAR,
     max_size: Optional[int] = None,
 ) -> PIL.Image.Image:
-    return _FP.resize(img, size, interpolation=pil_modes_mapping[interpolation], max_size=max_size)
+    # TODO: use _compute_output_size to enable max_size option
+    max_size  # ununsed right now
+    return _FP.resize(img, size, interpolation=pil_modes_mapping[interpolation])
 
 
 def resize_segmentation_mask(

torchvision/transforms/functional.py

@@ -360,6 +360,29 @@ def normalize(tensor: Tensor, mean: List[float], std: List[float], inplace: bool
     return F_t.normalize(tensor, mean=mean, std=std, inplace=inplace)
 
 
+def _compute_output_size(image_size: Tuple[int, int], size: List[int], max_size: Optional[int] = None) -> List[int]:
+    if len(size) == 1:  # specified size only for the smallest edge
+        h, w = image_size
+        short, long = (w, h) if w <= h else (h, w)
+        requested_new_short = size if isinstance(size, int) else size[0]
+
+        new_short, new_long = requested_new_short, int(requested_new_short * long / short)
+
+        if max_size is not None:
+            if max_size <= requested_new_short:
+                raise ValueError(
+                    f"max_size = {max_size} must be strictly greater than the requested "
+                    f"size for the smaller edge size = {size}"
+                )
+            if new_long > max_size:
+                new_short, new_long = int(max_size * new_short / new_long), max_size
+
+        new_w, new_h = (new_short, new_long) if w <= h else (new_long, new_short)
+    else:  # specified both h and w
+        new_w, new_h = size[1], size[0]
+    return [new_h, new_w]
+
+
 def resize(
     img: Tensor,
     size: List[int],
@@ -423,13 +446,32 @@ def resize(
     if not isinstance(interpolation, InterpolationMode):
         raise TypeError("Argument interpolation should be a InterpolationMode")
 
+    if isinstance(size, (list, tuple)):
+        if len(size) not in [1, 2]:
+            raise ValueError(
+                f"Size must be an int or a 1 or 2 element tuple/list, not a {len(size)} element tuple/list"
+            )
+        if max_size is not None and len(size) != 1:
+            raise ValueError(
+                "max_size should only be passed if size specifies the length of the smaller edge, "
+                "i.e. size should be an int or a sequence of length 1 in torchscript mode."
+            )
+
+    _, image_height, image_width = get_dimensions(img)
+    if isinstance(size, int):
+        size = [size]
+    output_size = _compute_output_size((image_height, image_width), size, max_size)
+
+    if (image_height, image_width) == output_size:
+        return img
+
     if not isinstance(img, torch.Tensor):
         if antialias is not None and not antialias:
             warnings.warn("Anti-alias option is always applied for PIL Image input. Argument antialias is ignored.")
         pil_interpolation = pil_modes_mapping[interpolation]
-        return F_pil.resize(img, size=size, interpolation=pil_interpolation, max_size=max_size)
+        return F_pil.resize(img, size=output_size, interpolation=pil_interpolation)
 
-    return F_t.resize(img, size=size, interpolation=interpolation.value, max_size=max_size, antialias=antialias)
+    return F_t.resize(img, size=output_size, interpolation=interpolation.value, antialias=antialias)
 
 
 def pad(img: Tensor, padding: List[int], fill: int = 0, padding_mode: str = "constant") -> Tensor:

torchvision/transforms/functional_pil.py

 import numbers
-from typing import Any, Dict, List, Optional, Sequence, Tuple, Union
+from typing import Any, Dict, List, Optional, Tuple, Union
 
 import numpy as np
 import torch
@@ -240,46 +240,16 @@ def crop(
 @torch.jit.unused
 def resize(
     img: Image.Image,
-    size: Union[Sequence[int], int],
+    size: Union[List[int], int],
     interpolation: int = _pil_constants.BILINEAR,
-    max_size: Optional[int] = None,
 ) -> Image.Image:
 
     if not _is_pil_image(img):
         raise TypeError(f"img should be PIL Image. Got {type(img)}")
-    if not (isinstance(size, int) or (isinstance(size, Sequence) and len(size) in (1, 2))):
+    if not (isinstance(size, list) and len(size) == 2):
         raise TypeError(f"Got inappropriate size arg: {size}")
 
-    if isinstance(size, Sequence) and len(size) == 1:
-        size = size[0]
-    if isinstance(size, int):
-        w, h = img.size
-
-        short, long = (w, h) if w <= h else (h, w)
-        new_short, new_long = size, int(size * long / short)
-
-        if max_size is not None:
-            if max_size <= size:
-                raise ValueError(
-                    f"max_size = {max_size} must be strictly greater than the requested "
-                    f"size for the smaller edge size = {size}"
-                )
-            if new_long > max_size:
-                new_short, new_long = int(max_size * new_short / new_long), max_size
-
-        new_w, new_h = (new_short, new_long) if w <= h else (new_long, new_short)
-
-        if (w, h) == (new_w, new_h):
-            return img
-        else:
-            return img.resize((new_w, new_h), interpolation)
-    else:
-        if max_size is not None:
-            raise ValueError(
-                "max_size should only be passed if size specifies the length of the smaller edge, "
-                "i.e. size should be an int or a sequence of length 1 in torchscript mode."
-            )
-        return img.resize(size[::-1], interpolation)
+    return img.resize(size[::-1], interpolation)
 
 
 @torch.jit.unused

torchvision/transforms/functional_tensor.py

@@ -430,70 +430,25 @@ def resize(
     img: Tensor,
     size: List[int],
     interpolation: str = "bilinear",
-    max_size: Optional[int] = None,
     antialias: Optional[bool] = None,
 ) -> Tensor:
     _assert_image_tensor(img)
 
-    if not isinstance(size, (int, tuple, list)):
-        raise TypeError("Got inappropriate size arg")
-    if not isinstance(interpolation, str):
-        raise TypeError("Got inappropriate interpolation arg")
-
-    if interpolation not in ["nearest", "bilinear", "bicubic"]:
-        raise ValueError("This interpolation mode is unsupported with Tensor input")
-
     if isinstance(size, tuple):
         size = list(size)
 
-    if isinstance(size, list):
-        if len(size) not in [1, 2]:
-            raise ValueError(
-                f"Size must be an int or a 1 or 2 element tuple/list, not a {len(size)} element tuple/list"
-            )
-        if max_size is not None and len(size) != 1:
-            raise ValueError(
-                "max_size should only be passed if size specifies the length of the smaller edge, "
-                "i.e. size should be an int or a sequence of length 1 in torchscript mode."
-            )
-
     if antialias is None:
         antialias = False
 
     if antialias and interpolation not in ["bilinear", "bicubic"]:
         raise ValueError("Antialias option is supported for bilinear and bicubic interpolation modes only")
 
-    _, h, w = get_dimensions(img)
-
-    if isinstance(size, int) or len(size) == 1:  # specified size only for the smallest edge
-        short, long = (w, h) if w <= h else (h, w)
-        requested_new_short = size if isinstance(size, int) else size[0]
-
-        new_short, new_long = requested_new_short, int(requested_new_short * long / short)
-
-        if max_size is not None:
-            if max_size <= requested_new_short:
-                raise ValueError(
-                    f"max_size = {max_size} must be strictly greater than the requested "
-                    f"size for the smaller edge size = {size}"
-                )
-            if new_long > max_size:
-                new_short, new_long = int(max_size * new_short / new_long), max_size
-
-        new_w, new_h = (new_short, new_long) if w <= h else (new_long, new_short)
-
-        if (w, h) == (new_w, new_h):
-            return img
-
-    else:  # specified both h and w
-        new_w, new_h = size[1], size[0]
-
     img, need_cast, need_squeeze, out_dtype = _cast_squeeze_in(img, [torch.float32, torch.float64])
 
     # Define align_corners to avoid warnings
     align_corners = False if interpolation in ["bilinear", "bicubic"] else None
 
-    img = interpolate(img, size=[new_h, new_w], mode=interpolation, align_corners=align_corners, antialias=antialias)
+    img = interpolate(img, size=size, mode=interpolation, align_corners=align_corners, antialias=antialias)
 
     if interpolation == "bicubic" and out_dtype == torch.uint8:
         img = img.clamp(min=0, max=255)