Scriptable Resize Added

test/test_functional_tensor.py

@@ -138,6 +138,36 @@ def test_ten_crop(self):
                                     (transforms.ToTensor()(cropped_pil_image[9]) * 255).to(torch.uint8)))
         self.assertTrue(torch.equal(img_tensor, img_tensor_clone))
 
+    def test_resize(self):
+        height = random.randint(24, 32) * 2
+        width = random.randint(24, 32) * 2
+        img = torch.ones(3, height, width)
+        img_clone = img.clone()
+        modes = ["bilinear", "nearest", "bicubic"]
+
+        for mode in modes:
+            # (Int) for resizing
+            output_size = random.randint(5, 12) * 2
+            result = F_t.resize(img, output_size, interpolation=mode)
+            if height < width:
+                self.assertEqual(output_size, result.shape[1])
+            else:
+                self.assertEqual(output_size, result.shape[2])
+
+            # (Int, Int) for resizing
+            output_size = (random.randint(5, 12) * 2, random.randint(5, 12) * 2)
+            result = F_t.resize(img, output_size, interpolation=mode)
+            self.assertEqual((output_size[0], output_size[1]), (result.shape[1], result.shape[2]))
+
+        # checking input tensor is not mutated
+        self.assertTrue(torch.equal(img, img_clone))
+
+        # checking overshooting for bicubic
+        output_size = (random.randint(5, 12) * 2, random.randint(5, 12) * 2)
+        result = F_t.resize(img, output_size, interpolation="bicubic")
+        clamped_tensor = result.clamp(min=0, max=255)
+        self.assertTrue(torch.equal(result, clamped_tensor))
+
 
 if __name__ == '__main__':
     unittest.main()

torchvision/transforms/functional_tensor.py

@@ -1,5 +1,6 @@
 import torch
 import torchvision.transforms.functional as F
+import torch.nn.functional as Fn
 
 
 def vflip(img_tensor):
@@ -219,3 +220,40 @@ def ten_crop(img, size, vertical_flip=False):
 def _blend(img1, img2, ratio):
     bound = 1 if img1.dtype.is_floating_point else 255
     return (ratio * img1 + (1 - ratio) * img2).clamp(0, bound).to(img1.dtype)
+
+
+def resize(img, size, interpolation="bilinear"):
+    r"""Resize the input Tensor Image to the given size.
+
+    Args:
+        img (Tensor): Image to be resized.
+        size (sequence or int): Desired output size. If size is a sequence like
+            (h, w), the output size will be matched to this. If size is an int,
+            the smaller edge of the image will be matched to this number maintaing
+            the aspect ratio. i.e, if height > width, then image will be rescaled to
+            :math:`\left(\text{size} \times \frac{\text{height}}{\text{width}}, \text{size}\right)`
+        interpolation (string, optional): Desired interpolation ["bilinear", "nearest", "bicubic"]. Default is
+            ``bilinear``
+
+    Returns:
+         Tensor: Resized image Tensor.
+    """
+    if not F._is_tensor_image(img):
+        raise TypeError('tensor is not a torch image.')
+
+    if isinstance(size, int):
+        w, h = img.shape[2], img.shape[1]
+        if (w <= h and w == size) or (h <= w and h == size):
+            return img
+        if w < h:
+            ow = size
+            oh = int(size * h / w)
+            out_img = Fn.interpolate(img.unsqueeze(0), size=(oh, ow), mode=interpolation)
+        else:
+            oh = size
+            ow = int(size * w / h)
+            out_img = Fn.interpolate(img.unsqueeze(0), size=(oh, ow), mode=interpolation)
+    else:
+        out_img = Fn.interpolate(img.unsqueeze(0), size=size, mode=interpolation)
+
+    return(out_img.clamp(min=0, max=255).squeeze(0))