Changeset 23231

Timestamp:

Mar 9, 2009, 12:58:27 PM (17 years ago)

Author:

Paul Price

Message:

Lanczos kernel wasn't being calculated correctly, resulting in
smoothed output images. The fixed code produces images that aren't as
smoothed: the covariance matrix goes from 1 in the centre to 0.1 for
the nearby pixels, compared to 0.5 before the fix.

File:

• trunk/psLib/src/imageops/psImageInterpolate.c (modified) (1 diff)

trunk/psLib/src/imageops/psImageInterpolate.c

@@ -133 +133 @@
     }
 
-    float norm1 = 2.0 / PS_SQR(M_PI); // Normalisation for laczos
-    float norm2 = M_PI * 4.0 / (float)size; // Normalisation for sinc function 1
-    float norm3 = M_PI_2 * 4.0 / (float)size; // Normalisation for sinc function 2
+    float norm1 = size / 2.0 / PS_SQR(M_PI); // Normalisation for laczos
+    float norm2 = M_PI;                 // Normalisation for sinc function 1
+    float norm3 = M_PI * 2.0 / (float)size; // Normalisation for sinc function 2
     float pos = - (size - 1)/2 - frac;  // Position of interest
     for (int i = 0; i < size; i++, pos += 1.0) {