Merge branch 'fix-blur-alpha'

Tests/test_imageops_usm.py

@@ -5,6 +5,7 @@ from PIL import ImageOps
 from PIL import ImageFilter
 
 im = Image.open("Tests/images/hopper.ppm")
+snakes = Image.open("Tests/images/color_snakes.png")
 
 
 class TestImageOpsUsm(PillowTestCase):
@@ -16,7 +17,7 @@ class TestImageOpsUsm(PillowTestCase):
         self.assertEqual(i.size, (128, 128))
         # i.save("blur.bmp")
 
-        i = ImageOps.usm(im, 2.0, 125, 8)
+        i = ImageOps.unsharp_mask(im, 2.0, 125, 8)
         self.assertEqual(i.mode, "RGB")
         self.assertEqual(i.size, (128, 128))
         # i.save("usm.bmp")
@@ -33,7 +34,7 @@ class TestImageOpsUsm(PillowTestCase):
         self.assertEqual(i.mode, "RGB")
         self.assertEqual(i.size, (128, 128))
 
-    def test_usm(self):
+    def test_usm_formats(self):
 
         usm = ImageOps.unsharp_mask
         self.assertRaises(ValueError, lambda: usm(im.convert("1")))
@@ -45,7 +46,7 @@ class TestImageOpsUsm(PillowTestCase):
         usm(im.convert("CMYK"))
         self.assertRaises(ValueError, lambda: usm(im.convert("YCbCr")))
 
-    def test_blur(self):
+    def test_blur_formats(self):
 
         blur = ImageOps.gaussian_blur
         self.assertRaises(ValueError, lambda: blur(im.convert("1")))
@@ -57,6 +58,33 @@ class TestImageOpsUsm(PillowTestCase):
         blur(im.convert("CMYK"))
         self.assertRaises(ValueError, lambda: blur(im.convert("YCbCr")))
 
+    def test_usm_accuracy(self):
+
+        i = snakes._new(ImageOps.unsharp_mask(snakes, 5, 1024, 0))
+        # Image should not be changed because it have only 0 and 255 levels.
+        self.assertEqual(i.tobytes(), snakes.tobytes())
+
+    def test_blur_accuracy(self):
+
+        i = snakes._new(ImageOps.gaussian_blur(snakes, 1))
+        # Alpha channel must match whole.
+        self.assertEqual(i.split()[3], snakes.split()[3])
+        # These pixels surrounded with pixels with 255 intensity.
+        # They must be 255.
+        for x, y, c in [(1, 0, 1), (2, 0, 1), (7, 8, 1), (8, 8, 1), (2, 9, 1),
+                        (7, 3, 0), (8, 3, 0), (5, 8, 0), (5, 9, 0), (1, 3, 0),
+                        (4, 3, 2), (4, 2, 2)]:
+            self.assertEqual(i.im.getpixel((x, y))[c], 255)
+        # Fuzzy match.
+        gp = lambda x, y: i.im.getpixel((x, y))
+        self.assertTrue(211 <= gp(7, 4)[0] <= 213)
+        self.assertTrue(211 <= gp(7, 5)[2] <= 213)
+        self.assertTrue(211 <= gp(7, 6)[2] <= 213)
+        self.assertTrue(211 <= gp(7, 7)[1] <= 213)
+        self.assertTrue(211 <= gp(8, 4)[0] <= 213)
+        self.assertTrue(211 <= gp(8, 5)[2] <= 213)
+        self.assertTrue(211 <= gp(8, 6)[2] <= 213)
+        self.assertTrue(211 <= gp(8, 7)[1] <= 213)
 
 if __name__ == '__main__':
     unittest.main()

libImaging/UnsharpMask.c

@@ -51,7 +51,7 @@ static inline UINT8 clip(double in)
         return (UINT8) 255;
     if (in <= 0.0)
         return (UINT8) 0;
-    return (UINT8) in;
+    return (UINT8) (in + 0.5);
 }
 
 static Imaging
@@ -79,6 +79,7 @@ gblur(Imaging im, Imaging imOut, float floatRadius, int channels, int padding)
 
     int radius = 0;
     float remainder = 0.0;
+    int hasAlpha = 0;
 
     int i;
 
@@ -189,6 +190,10 @@ gblur(Imaging im, Imaging imOut, float floatRadius, int channels, int padding)
         }
     }
 
+    if (strcmp(im->mode, "RGBX") == 0 || strcmp(im->mode, "RGBA") == 0) {
+        hasAlpha = 1;
+    }
+
     /* perform a blur on each column in the buffer, and place in the
        output image */
     for (x = 0; x < im->xsize; x++) {
@@ -204,6 +209,7 @@ gblur(Imaging im, Imaging imOut, float floatRadius, int channels, int padding)
                     offset = -y;
                 else if (y + offset >= im->ysize)
                     offset = im->ysize - y - 1;
+
                 /* add (neighbor pixel value * maskData[pix]) to the current
                    pixel value */
                 for (channel = 0; channel < channels; channel++) {
@@ -215,9 +221,8 @@ gblur(Imaging im, Imaging imOut, float floatRadius, int channels, int padding)
             }
             /* if the image is RGBX or RGBA, copy the 4th channel data to
                newPixel, so it gets put in imOut */
-	    if (strcmp(im->mode, "RGBX") == 0
-		|| strcmp(im->mode, "RGBA") == 0) {
-	      newPixel[3] = (float) ((UINT8 *) & line[x + offset])[3];
+            if (hasAlpha) {
+                newPixel[3] = (float) ((UINT8 *) & im->image32[y][x])[3];
             }
 
             /* pack the channels into an INT32 so we can put them back in
@@ -288,6 +293,7 @@ ImagingUnsharpMask(Imaging im, Imaging imOut, float radius, int percent,
     int channel = 0;
     int channels = 0;
     int padding = 0;
+    int hasAlpha = 0;
 
     int x = 0;
     int y = 0;
@@ -332,6 +338,10 @@ ImagingUnsharpMask(Imaging im, Imaging imOut, float radius, int percent,
 
     ImagingSectionEnter(&cookie);
 
+    if (strcmp(im->mode, "RGBX") == 0 || strcmp(im->mode, "RGBA") == 0) {
+        hasAlpha = 1;
+    }
+
     for (y = 0; y < im->ysize; y++) {
         if (channels == 1) {
             lineIn8 = im->image8[y];
@@ -380,8 +390,7 @@ ImagingUnsharpMask(Imaging im, Imaging imOut, float radius, int percent,
                             (channel * 8);
                     }
                 }
-		if (strcmp(im->mode, "RGBX") == 0
-		    || strcmp(im->mode, "RGBA") == 0) {
+                if (hasAlpha) {
                     /* preserve the alpha channel
                        this may not work for little-endian systems, fix it! */
                     newPixel =