Changeset 21316 for trunk/psLib/src/imageops/psImageCovariance.h

Timestamp:

Feb 5, 2009, 10:15:32 AM (17 years ago)

Author:

Paul Price

Message:

Adding function to truncate a covariance matrix. This should help to keep them from growing too large (we're using kernels of half-size ~ 15 pixels for stack, which makes the covariance matrix grow by 60 pixels, which puts a big stress on psImageCovarianceCalculate).

File:

• trunk/psLib/src/imageops/psImageCovariance.h (modified) (3 diffs)

trunk/psLib/src/imageops/psImageCovariance.h

@@ -5 +5 @@
  * @author Paul Price, IfA
  *
- * @version $Revision: 1.3 $ $Name: not supported by cvs2svn $
- * @date $Date: 2009-02-05 00:42:48 $
+ * @version $Revision: 1.4 $ $Name: not supported by cvs2svn $
+ * @date $Date: 2009-02-05 20:15:32 $
  * Copyright 2009 Institute for Astronomy, University of Hawaii
  */
@@ -21 +21 @@
 // storage difficult; and if that's not enough, the time to do the calculation is definitely impractical).
 // Since there are (generally) lots of zeros in the covariance matrix, and the same basic pattern repeats (for
-// background pixels), we can just carry that pattern.  We carry this in a psKernel, since the values are the
-// covariance between the pixel of consideration (at 0,0 in the kernel) and neighbouring pixels.  Note that
-// this may not be strictly correct near sources, but this is the best we can do (and much better than most
-// currently do).
+// background pixels), we can just carry that pattern ("covariance pseudo-matrix").  We carry this in a
+// psKernel, since the values are the covariance between the pixel of consideration (at 0,0 in the kernel) and
+// neighbouring pixels.  Note that this may not be strictly correct near sources, but this is the best we can
+// do (and much better than most currently do).
 
 /// Allocate a covariance pseudo-matrix with no covariance
@@ -50 +50 @@
     );
 
+/// Truncate covariance pseudo-matrix
+///
+/// The covariance pseudo-matrix is truncated by removing the outer regions that contribute less than the
+/// nominated fraction of the total.
+psKernel *psImageCovarianceTruncate(
+    const psKernel *covar,              ///< Covariance pseudo-matrix
+    float frac                          ///< Fraction of covariance to truncate
+    );
 
 /// @}