Changeset 2719

Timestamp:

08/14/08 20:35:07 (5 years ago)

Author:

sam

Message:

• blur.c: improve the Gaussian kernel generation by interpolating its values in a quincunx pattern.

File:

• libpipi/trunk/pipi/filter/blur.c (modified) (1 diff)

libpipi/trunk/pipi/filter/blur.c

@@ -72 +72 @@
         for(i = -krx; i <= krx; i++)
         {
-            double u = (double)i * cost - (double)j * sint + dx;
-            double v = (double)j * cost + (double)i * sint + dy;
-            double ex = Kx * u * u;
-            double ey = Ky * v * v;
-            double d = exp(ex + ey);
+            static double const samples[] =
+            {
+                -.50, -.50, 0.5,
+                 .50, -.50, 0.5,
+                 .0,  .0, 1,
+                -.50,  .50, 0.5,
+                 .50,  .50, 0.5
+            };
+            double u, v, ex, ey, d = 0.;
+            int k;
+
+            for(k = 0; k < 5; k++)
+            {
+                u = ((double)i + samples[k * 3]) * cost
+                     - ((double)j + samples[k * 3 + 1]) * sint + dx;
+                v = ((double)i + samples[k * 3]) * sint
+                     + ((double)j + samples[k * 3 + 1]) * cost + dy;
+                ex = Kx * u * u;
+                ey = Ky * v * v;
+                d += samples[k * 3 + 2] * exp(ex + ey);
+            }
 
             kernel[(j + kry) * m + i + krx] = d;