Added ImageOps exif_transpose method

Tests/test_imageops.py

@@ -3,6 +3,12 @@
 from PIL import ImageOps
 from PIL import Image
 
+try:
+    from PIL import _webp
+    HAVE_WEBP = True
+except ImportError:
+    HAVE_WEBP = False
+
 
 class TestImageOps(PillowTestCase):
 
@@ -62,6 +68,9 @@ def test_sanity(self):
         ImageOps.solarize(hopper("L"))
         ImageOps.solarize(hopper("RGB"))
 
+        ImageOps.exif_transpose(hopper("L"))
+        ImageOps.exif_transpose(hopper("RGB"))
+
     def test_1pxfit(self):
         # Division by zero in equalize if image is 1 pixel high
         newimg = ImageOps.fit(hopper("RGB").resize((1, 1)), (35, 35))
@@ -218,3 +227,22 @@ def test_colorize_3color_offset(self):
                                        (0, 127, 0),
                                        threshold=1,
                                        msg='white test pixel incorrect')
+
+    def test_exif_transpose(self):
+        exts = [".jpg"]
+        if HAVE_WEBP and _webp.HAVE_WEBPANIM:
+            exts.append(".webp")
+        for ext in exts:
+            base_im = Image.open("Tests/images/hopper"+ext)
+
+            orientations = [base_im]
+            for i in range(2, 9):
+                im = Image.open("Tests/images/hopper_orientation_"+str(i)+ext)
+                orientations.append(im)
+            for im in orientations:
+                transposed_im = ImageOps.exif_transpose(im)
+                self.assert_image_similar(base_im, transposed_im, 17)
+
+                # Repeat the operation, to test that it does not keep transposing
+                transposed_im2 = ImageOps.exif_transpose(transposed_im)
+                self.assert_image_equal(transposed_im2, transposed_im)

src/PIL/ImageOps.py

@@ -522,3 +522,31 @@ def solarize(image, threshold=128):
         else:
             lut.append(255-i)
     return _lut(image, lut)
+
+
+def exif_transpose(image):
+    """
+    If an image has an EXIF Orientation tag, return a new image that is
+    transposed accordingly. Otherwise, return a copy of the image.
+
+    :param image: The image to transpose.
+    :return: An image.
+    """
+    if not hasattr(image, '_exif_transposed') and hasattr(image, '_getexif'):
+        exif = image._getexif()
+        if exif:
+            orientation = exif.get(0x0112)
+            method = {
+                2: Image.FLIP_LEFT_RIGHT,
+                3: Image.ROTATE_180,
+                4: Image.FLIP_TOP_BOTTOM,
+                5: Image.TRANSPOSE,
+                6: Image.ROTATE_270,
+                7: Image.TRANSVERSE,
+                8: Image.ROTATE_90
+            }.get(orientation)
+            if method is not None:
+                transposed_image = image.transpose(method)
+                transposed_image._exif_transposed = True
+                return transposed_image
+    return image.copy()