From 4241539d6c39f8ccf75869a81f046f6f98e527c7 Mon Sep 17 00:00:00 2001
From: Amy Roberts <22614925+amyeroberts@users.noreply.github.com>
Date: Mon, 6 Mar 2023 14:15:30 +0000
Subject: [PATCH 1/3] Add check before int casting for PIL conversion

---
 src/transformers/image_transforms.py | 13 +++++++++++--
 tests/test_image_transforms.py       |  5 +++++
 2 files changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/transformers/image_transforms.py b/src/transformers/image_transforms.py
index 0ae19c43c74a..d9fd6bf4cac2 100644
--- a/src/transformers/image_transforms.py
+++ b/src/transformers/image_transforms.py
@@ -131,7 +131,8 @@ def to_pil_image(
             The image to convert to the `PIL.Image` format.
         do_rescale (`bool`, *optional*):
             Whether or not to apply the scaling factor (to make pixel values integers between 0 and 255). Will default
-            to `True` if the image type is a floating type, `False` otherwise.
+            to `True` if the image type is a floating type and casting to `int` would result in a loss of precision, and
+            `False` otherwise.
 
     Returns:
         `PIL.Image.Image`: The converted image.
@@ -156,9 +157,17 @@ def to_pil_image(
     image = np.squeeze(image, axis=-1) if image.shape[-1] == 1 else image
 
     # PIL.Image can only store uint8 values, so we rescale the image to be between 0 and 255 if needed.
-    do_rescale = isinstance(image.flat[0], (float, np.float32, np.float64)) if do_rescale is None else do_rescale
+    if do_rescale is None:
+        do_rescale = isinstance(image.flat[0], (float, np.floating)) and not np.allclose(image, image.astype(int))
+
     if do_rescale:
         image = rescale(image, 255)
+
+    if np.any(image < 0) or np.any(image > 255):
+        raise ValueError(
+            "The image to be converted to a PIL image contains values outside the range [0, 255], "
+            f"got [{image.min()}, {image.max()}] which cannot be converted to uint8."
+        )
     image = image.astype(np.uint8)
     return PIL.Image.fromarray(image)
 
diff --git a/tests/test_image_transforms.py b/tests/test_image_transforms.py
index 2287fdbf2ce9..0efefc7c8fbb 100644
--- a/tests/test_image_transforms.py
+++ b/tests/test_image_transforms.py
@@ -96,6 +96,11 @@ def test_to_pil_image_from_float(self, name, image_shape, dtype):
         # make sure image is correctly rescaled
         self.assertTrue(np.abs(np.asarray(pil_image)).sum() > 0)
 
+        # Make sure that an exception is raised if image is not in [0, 1]
+        image = np.random.randn(*image_shape).astype(dtype)
+        with self.assertRaises(ValueError):
+            to_pil_image(image)
+
     @require_tf
     def test_to_pil_image_from_tensorflow(self):
         # channels_first

From c33f9fde9e6a9f9116e5d0f6ccb59aa89039f579 Mon Sep 17 00:00:00 2001
From: Amy Roberts <22614925+amyeroberts@users.noreply.github.com>
Date: Mon, 6 Mar 2023 15:10:56 +0000
Subject: [PATCH 2/3] Line length

---
 src/transformers/image_transforms.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/src/transformers/image_transforms.py b/src/transformers/image_transforms.py
index d9fd6bf4cac2..b679e0bc3aad 100644
--- a/src/transformers/image_transforms.py
+++ b/src/transformers/image_transforms.py
@@ -131,8 +131,8 @@ def to_pil_image(
             The image to convert to the `PIL.Image` format.
         do_rescale (`bool`, *optional*):
             Whether or not to apply the scaling factor (to make pixel values integers between 0 and 255). Will default
-            to `True` if the image type is a floating type and casting to `int` would result in a loss of precision, and
-            `False` otherwise.
+            to `True` if the image type is a floating type and casting to `int` would result in a loss of precision,
+            and `False` otherwise.
 
     Returns:
         `PIL.Image.Image`: The converted image.

From 2304eb6e0fd6cd0f19fbbe24cfd7e63fd6913ec1 Mon Sep 17 00:00:00 2001
From: Amy Roberts <22614925+amyeroberts@users.noreply.github.com>
Date: Tue, 7 Mar 2023 10:55:24 +0000
Subject: [PATCH 3/3] Tidier logic

---
 src/transformers/image_transforms.py | 15 +++++++++------
 1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/src/transformers/image_transforms.py b/src/transformers/image_transforms.py
index b679e0bc3aad..16016d97042c 100644
--- a/src/transformers/image_transforms.py
+++ b/src/transformers/image_transforms.py
@@ -158,16 +158,19 @@ def to_pil_image(
 
     # PIL.Image can only store uint8 values, so we rescale the image to be between 0 and 255 if needed.
     if do_rescale is None:
-        do_rescale = isinstance(image.flat[0], (float, np.floating)) and not np.allclose(image, image.astype(int))
+        if np.all(0 <= image) and np.all(image <= 1):
+            do_rescale = True
+        elif np.allclose(image, image.astype(int)):
+            do_rescale = False
+        else:
+            raise ValueError(
+                "The image to be converted to a PIL image contains values outside the range [0, 1], "
+                f"got [{image.min()}, {image.max()}] which cannot be converted to uint8."
+            )
 
     if do_rescale:
         image = rescale(image, 255)
 
-    if np.any(image < 0) or np.any(image > 255):
-        raise ValueError(
-            "The image to be converted to a PIL image contains values outside the range [0, 255], "
-            f"got [{image.min()}, {image.max()}] which cannot be converted to uint8."
-        )
     image = image.astype(np.uint8)
     return PIL.Image.fromarray(image)