Added PerspectiveTransform

Tests/test_image_transform.py

@@ -10,18 +10,25 @@
 
 class TestImageTransform:
     def test_sanity(self):
-        im = Image.new("L", (100, 100))
-
-        seq = tuple(range(10))
-
-        transform = ImageTransform.AffineTransform(seq[:6])
-        im.transform((100, 100), transform)
-        transform = ImageTransform.ExtentTransform(seq[:4])
-        im.transform((100, 100), transform)
-        transform = ImageTransform.QuadTransform(seq[:8])
-        im.transform((100, 100), transform)
-        transform = ImageTransform.MeshTransform([(seq[:4], seq[:8])])
-        im.transform((100, 100), transform)
+        im = hopper()
+
+        for transform in (
+            ImageTransform.AffineTransform((1, 0, 0, 0, 1, 0)),
+            ImageTransform.PerspectiveTransform((1, 0, 0, 0, 1, 0, 0, 0)),
+            ImageTransform.ExtentTransform((0, 0) + im.size),
+            ImageTransform.QuadTransform(
+                (0, 0, 0, im.height, im.width, im.height, im.width, 0)
+            ),
+            ImageTransform.MeshTransform(
+                [
+                    (
+                        (0, 0) + im.size,
+                        (0, 0, 0, im.height, im.width, im.height, im.width, 0),
+                    )
+                ]
+            ),
+        ):
+            assert_image_equal(im, im.transform(im.size, transform))
 
     def test_info(self):
         comment = b"File written by Adobe Photoshop\xa8 4.0"

docs/reference/ImageTransform.rst

@@ -19,6 +19,11 @@ The :py:mod:`~PIL.ImageTransform` module contains implementations of
     :undoc-members:
     :show-inheritance:
 
+.. autoclass:: PerspectiveTransform
+    :members:
+    :undoc-members:
+    :show-inheritance:
+
 .. autoclass:: ExtentTransform
     :members:
     :undoc-members:

src/PIL/ImageTransform.py

@@ -63,6 +63,26 @@ class AffineTransform(Transform):
     method = Image.Transform.AFFINE
 
 
+class PerspectiveTransform(Transform):
+    """
+    Define a perspective image transform.
+
+    This function takes an 8-tuple (a, b, c, d, e, f, g, h). For each pixel
+    (x, y) in the output image, the new value is taken from a position
+    ((a x + b y + c) / (g x + h y + 1), (d x + e y + f) / (g x + h y + 1)) in
+    the input image, rounded to nearest pixel.
+
+    This function can be used to scale, translate, rotate, and shear the
+    original image.
+
+    See :py:meth:`.Image.transform`
+
+    :param matrix: An 8-tuple (a, b, c, d, e, f, g, h).
+    """
+
+    method = Image.Transform.PERSPECTIVE
+
+
 class ExtentTransform(Transform):
     """
     Define a transform to extract a subregion from an image.