* blur.c: improve the Gaussian kernel interpolation.

git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@2737 92316355-f0b4-4df1-b90c-862c8a59935f

pipi/filter/blur.c

@@ -71,18 +71,24 @@ pipi_image_t *pipi_gaussian_blur_ext(pipi_image_t *src, float rx, float ry,
     {
         for(i = -krx; i <= krx; i++)
         {
+            /* FIXME: this level of interpolation sucks. We should
+             * interpolate on the full NxN grid for better quality. */
             static double const samples[] =
             {
-                -.50, -.50, 0.5,
-                 .50, -.50, 0.5,
                  .0,  .0, 1,
-                -.50,  .50, 0.5,
-                 .50,  .50, 0.5
+                -.40, -.40, 0.8,
+                -.30,  .0,  0.9,
+                -.40,  .40, 0.8,
+                 .0,   .30, 0.9,
+                 .40,  .40, 0.8,
+                 .30,  .0,  0.9,
+                 .40, -.40, 0.8,
+                 .0,  -.30, 0.9,
             };
             double u, v, ex, ey, d = 0.;
-            int k;
+            unsigned int k;
 
-            for(k = 0; k < 5; k++)
+            for(k = 0; k < sizeof(samples) / sizeof(*samples) / 3; k++)
             {
                 u = ((double)i + samples[k * 3]) * cost
                      - ((double)j + samples[k * 3 + 1]) * sint + dx;