Fast filters

PIL/Image.py

@@ -1105,6 +1105,8 @@ def filter(self, filter):
         :param filter: Filter kernel.
         :returns: An :py:class:`~PIL.Image.Image` object.  """
 
+        from . import ImageFilter
+
         self.load()
 
         if isinstance(filter, collections.Callable):
@@ -1113,9 +1115,10 @@ def filter(self, filter):
             raise TypeError("filter argument should be ImageFilter.Filter " +
                             "instance or class")
 
-        if self.im.bands == 1:
+        multiband = isinstance(filter, ImageFilter.MultibandFilter)
+        if self.im.bands == 1 or multiband:
             return self._new(filter.filter(self.im))
-        # fix to handle multiband images since _imaging doesn't
+
         ims = []
         for c in range(self.im.bands):
             ims.append(self._new(filter.filter(self.im.getband(c))))

PIL/ImageFilter.py

@@ -22,7 +22,11 @@ class Filter(object):
     pass
 
 
-class Kernel(Filter):
+class MultibandFilter(Filter):
+    pass
+
+
+class Kernel(MultibandFilter):
     """
     Create a convolution kernel.  The current version only
     supports 3x3 and 5x5 integer and floating point kernels.
@@ -142,7 +146,7 @@ def filter(self, image):
         return image.modefilter(self.size)
 
 
-class GaussianBlur(Filter):
+class GaussianBlur(MultibandFilter):
     """Gaussian blur filter.
 
     :param radius: Blur radius.
@@ -156,7 +160,7 @@ def filter(self, image):
         return image.gaussian_blur(self.radius)
 
 
-class UnsharpMask(Filter):
+class UnsharpMask(MultibandFilter):
     """Unsharp mask filter.
 
     See Wikipedia's entry on `digital unsharp masking`_ for an explanation of

Tests/test_image_filter.py

@@ -95,26 +95,38 @@ def test_rankfilter_properties(self):
         self.assertEqual(rankfilter.rank, 2)
 
     def test_consistency_3x3(self):
-        im = Image.open("Tests/images/hopper.bmp")
-        emboss = im.filter(ImageFilter.Kernel((3, 3),
-            (-1, -1,  0,
-             -1,  0,  1,
-              0,  1,  1), .3))
-
-        self.assert_image_equal(
-            emboss, Image.open("Tests/images/hopper_emboss.bmp"))
+        source = Image.open("Tests/images/hopper.bmp")
+        reference = Image.open("Tests/images/hopper_emboss.bmp")
+        kernel = ImageFilter.Kernel((3, 3),
+                                    (-1, -1,  0,
+                                     -1,  0,  1,
+                                      0,  1,  1), .3)
+        source = source.split() * 2
+        reference = reference.split() * 2
+
+        for mode in ['L', 'LA', 'RGB', 'CMYK']:
+            self.assert_image_equal(
+                Image.merge(mode, source[:len(mode)]).filter(kernel),
+                Image.merge(mode, reference[:len(mode)]),
+            )
 
     def test_consistency_5x5(self):
-        im = Image.open("Tests/images/hopper.bmp")
-        emboss = im.filter(ImageFilter.Kernel((5, 5),
-            (-1, -1, -1, -1,  0,
-             -1, -1, -1,  0,  1,
-             -1, -1,  0,  1,  1,
-             -1,  0,  1,  1,  1,
-              0,  1,  1,  1,  1), 0.3))
-
-        self.assert_image_equal(
-            emboss, Image.open("Tests/images/hopper_emboss_more.bmp"))
+        source = Image.open("Tests/images/hopper.bmp")
+        reference = Image.open("Tests/images/hopper_emboss_more.bmp")
+        kernel = ImageFilter.Kernel((5, 5),
+                                    (-1, -1, -1, -1,  0,
+                                     -1, -1, -1,  0,  1,
+                                     -1, -1,  0,  1,  1,
+                                     -1,  0,  1,  1,  1,
+                                      0,  1,  1,  1,  1), 0.3)
+        source = source.split() * 2
+        reference = reference.split() * 2
+
+        for mode in ['L', 'LA', 'RGB', 'CMYK']:
+            self.assert_image_equal(
+                Image.merge(mode, source[:len(mode)]).filter(kernel),
+                Image.merge(mode, reference[:len(mode)]),
+            )
 
 
 if __name__ == '__main__':

_imaging.c

@@ -819,7 +819,7 @@ _filter(ImagingObject* self, PyObject* args)
     Py_ssize_t kernelsize;
     FLOAT32* kerneldata;
 
-    int xsize, ysize;
+    int xsize, ysize, i;
     float divisor, offset;
     PyObject* kernel = NULL;
     if (!PyArg_ParseTuple(args, "(ii)ffO", &xsize, &ysize,
@@ -835,8 +835,12 @@ _filter(ImagingObject* self, PyObject* args)
         return ImagingError_ValueError("bad kernel size");
     }
 
+    for (i = 0; i < kernelsize; ++i) {
+        kerneldata[i] /= divisor;
+    }
+
     imOut = PyImagingNew(
-        ImagingFilter(self->image, xsize, ysize, kerneldata, offset, divisor)
+        ImagingFilter(self->image, xsize, ysize, kerneldata, offset)
         );
 
     free(kerneldata);