Changeset 18298 for trunk/psLib/src/imageops/psImageInterpolate.c

Timestamp:

Jun 23, 2008, 4:01:55 PM (18 years ago)

Author:

Paul Price

Message:

Cleaning up lanczos

File:

• trunk/psLib/src/imageops/psImageInterpolate.c (modified) (2 diffs)

trunk/psLib/src/imageops/psImageInterpolate.c

@@ -7 +7 @@
  *  @author Paul Price, IfA
  *
- *  @version $Revision: 1.13 $ $Name: not supported by cvs2svn $
- *  @date $Date: 2008-06-24 01:47:14 $
+ *  @version $Revision: 1.14 $ $Name: not supported by cvs2svn $
+ *  @date $Date: 2008-06-24 02:01:55 $
  *
  *  Copyright 2004-2007 Institute for Astronomy, University of Hawaii
@@ -386 +386 @@
         }
     } else {
-        double norm3 = 0.0;             // Normalisation
+        double norm4 = 0.0;             // Normalisation
         double norm1 = 2.0 / PS_SQR(M_PI); // Normalisation for laczos
-        double norm2 = 4.0 / (float)num; // 2.0 / (num / 2);  // Normalisation for sinc functions
+        double norm2 = M_PI * 4.0 / (float)num; // Normalisation for sinc function 1
+        double norm3 =M_PI_2 * 4.0 / (float)num; // Normalisation for sinc function 2
         double pos = - (num - 1)/2 - frac;  // Position of interest
         for (int i = 0; i < num; i++, pos += 1.0) {
-            norm3 += values[i] = norm1 * sin(M_PI * pos * norm2) * sin(M_PI_2 * pos * norm2) / PS_SQR(pos);
-        }
-        norm3 = 1.0 / norm3;
-        for (int i = 0; i < num; i++, pos += 1.0) {
-            values[i] *= norm3;
+            norm4 += values[i] = norm1 * sin(pos * norm2) * sin(M_PI_2 * pos * norm3) / PS_SQR(pos);
+        }
+        norm4 = 1.0 / norm4
+        for (int i = 0; i < num; i++) {
+            values[i] *= norm4;
         }
     }