Add FiveCrop and TenCrop transforms (#261)

add FiveCrop and TenCrop

Author: alykhantejani

test/test_transforms.py

@@ -61,6 +61,66 @@ def test_crop(self):
         assert sum2 > sum1, "height: " + str(height) + " width: " \
                             + str(width) + " oheight: " + str(oheight) + " owidth: " + str(owidth)
 
+    def test_five_crop(self):
+        to_pil_image = transforms.ToPILImage()
+        h = random.randint(5, 25)
+        w = random.randint(5, 25)
+        for single_dim in [True, False]:
+            crop_h = random.randint(1, h)
+            crop_w = random.randint(1, w)
+            if single_dim:
+                crop_h = min(crop_h, crop_w)
+                crop_w = crop_h
+                transform = transforms.FiveCrop(crop_h)
+            else:
+                transform = transforms.FiveCrop((crop_h, crop_w))
+
+            img = torch.FloatTensor(3, h, w).uniform_()
+            results = transform(to_pil_image(img))
+
+            assert len(results) == 5
+            for crop in results:
+                assert crop.size == (crop_w, crop_h)
+
+            to_pil_image = transforms.ToPILImage()
+            tl = to_pil_image(img[:, 0:crop_h, 0:crop_w])
+            tr = to_pil_image(img[:, 0:crop_h, w - crop_w:])
+            bl = to_pil_image(img[:, h - crop_h:, 0:crop_w])
+            br = to_pil_image(img[:, h - crop_h:, w - crop_w:])
+            center = transforms.CenterCrop((crop_h, crop_w))(to_pil_image(img))
+            expected_output = (tl, tr, bl, br, center)
+            assert results == expected_output
+
+    def test_ten_crop(self):
+        to_pil_image = transforms.ToPILImage()
+        h = random.randint(5, 25)
+        w = random.randint(5, 25)
+        for should_vflip in [True, False]:
+            for single_dim in [True, False]:
+                crop_h = random.randint(1, h)
+                crop_w = random.randint(1, w)
+                if single_dim:
+                    crop_h = min(crop_h, crop_w)
+                    crop_w = crop_h
+                    transform = transforms.TenCrop(crop_h, vflip=should_vflip)
+                    five_crop = transforms.FiveCrop(crop_h)
+                else:
+                    transform = transforms.TenCrop((crop_h, crop_w), vflip=should_vflip)
+                    five_crop = transforms.FiveCrop((crop_h, crop_w))
+
+                img = to_pil_image(torch.FloatTensor(3, h, w).uniform_())
+                results = transform(img)
+                expected_output = five_crop(img)
+                if should_vflip:
+                    vflipped_img = img.transpose(Image.FLIP_TOP_BOTTOM)
+                    expected_output += five_crop(vflipped_img)
+                else:
+                    hflipped_img = img.transpose(Image.FLIP_LEFT_RIGHT)
+                    expected_output += five_crop(hflipped_img)
+
+                assert len(results) == 10
+                assert expected_output == results
+
     def test_scale(self):
         height = random.randint(24, 32) * 2
         width = random.randint(24, 32) * 2

torchvision/transforms.py

@@ -638,3 +638,72 @@ def __call__(self, img):
         """
         i, j, h, w = self.get_params(img)
         return scaled_crop(img, i, j, h, w, self.size, self.interpolation)
+
+
+class FiveCrop(object):
+    """Crop the given PIL.Image into four corners and the central crop.abs
+
+       Note: this transform returns a tuple of images and there may be a mismatch in the number of
+       inputs and targets your `Dataset` returns.
+
+       Args:
+           size (sequence or int): Desired output size of the crop. If size is an
+               int instead of sequence like (h, w), a square crop (size, size) is
+               made.
+    """
+
+    def __init__(self, size):
+        self.size = size
+        if isinstance(size, numbers.Number):
+            self.size = (int(size), int(size))
+        else:
+            assert len(size) == 2, "Please provide only two dimensions (h, w) for size."
+            self.size = size
+
+    def __call__(self, img):
+        w, h = img.size
+        crop_h, crop_w = self.size
+        if crop_w > w or crop_h > h:
+            raise ValueError("Requested crop size {} is bigger than input size {}".format(self.size,
+                                                                                          (h, w)))
+        tl = img.crop((0, 0, crop_w, crop_h))
+        tr = img.crop((w - crop_w, 0, w, crop_h))
+        bl = img.crop((0, h - crop_h, crop_w, h))
+        br = img.crop((w - crop_w, h - crop_h, w, h))
+        center = CenterCrop((crop_h, crop_w))(img)
+        return (tl, tr, bl, br, center)
+
+
+class TenCrop(object):
+    """Crop the given PIL.Image into four corners and the central crop plus the
+       flipped version of these (horizontal flipping is used by default)
+
+       Note: this transform returns a tuple of images and there may be a mismatch in the number of
+       inputs and targets your `Dataset` returns.
+
+       Args:
+           size (sequence or int): Desired output size of the crop. If size is an
+               int instead of sequence like (h, w), a square crop (size, size) is
+               made.
+           vflip bool: Use vertical flipping instead of horizontal
+    """
+
+    def __init__(self, size, vflip=False):
+        self.size = size
+        if isinstance(size, numbers.Number):
+            self.size = (int(size), int(size))
+        else:
+            assert len(size) == 2, "Please provide only two dimensions (h, w) for size."
+            self.size = size
+        self.vflip = vflip
+
+    def __call__(self, img):
+        five_crop = FiveCrop(self.size)
+        first_five = five_crop(img)
+        if self.vflip:
+            img = img.transpose(Image.FLIP_TOP_BOTTOM)
+        else:
+            img = img.transpose(Image.FLIP_LEFT_RIGHT)
+
+        second_five = five_crop(img)
+        return first_five + second_five