Changes between Version 7 and Version 8 of ppSubModifications_201009

Timestamp:

Sep 26, 2010, 11:42:09 AM (16 years ago)

Author:

eugene

Comment:

--

ppSubModifications_201009

@@ -54 +54 @@
 === more notes ===
 
-The pages that link from that page give a large number of examples using simulated image pairs spanning a wide range of PSF sizes and shapes.  There are examples using 3 different ppSub versions.  One set shows examples using the version which was used from the start of demo month until the end of August (labeled 20100701, which is the date of the last operations tag that used that algorithm).  The second set shows examples using the version which was used by the operational IPP from Aug 23 to the present (and future until we move the operational system to a new build), with the label 20100823 (the date of the operational tag).  Four other sets use the current version from my development branch, using labels with the date 20100918, when the algorithm changes were finished.  Just to be confusing, this last set comes from my development branch with the name branches/eam_branches/ipp-20100823 (the operational tag and my dev branch were created on the same day).
+The links above give a large number of examples using simulated image pairs spanning a wide range of PSF sizes and shapes.  There are examples using 3 different ppSub versions.  One set shows examples using the version which was used from the start of demo month until the end of August (labeled 20100701, which is the date of the last operations tag that used that algorithm).  The second set shows examples using the version which was used by the operational IPP from Aug 23 to the present (and future until we move the operational system to a new build), with the label 20100823 (the date of the operational tag).  Four other sets use the current version from my development branch, using labels with the date 20100918, when the algorithm changes were finished.  Just to be confusing, this last set comes from my development branch with the name branches/eam_branches/ipp-20100823 (the operational tag and my dev branch were created on the same day).
 
 The differences between the ppSub versions is mostly driven by the ambiguity in the dual convolution process.  The difference image is (effectively) constructed as A x k_A - B x k_B, where k_A and k_B involve the sums of the polynomial-modified Gaussians of different sizes.  For  a given pair of images, the kernels are not necessarily linearly independent, as it is possible to add terms to k_A and k_B which mutually smear both images.  (It is slightly more subtle than it sounds because the linear dependence of the kernel elements actually depends on the result of the convolution).  To break the degeneracy and to prevent excessive kernel growth, it is necessary to add something to the minimization linear algebra equation.  The different ppSub versions have some differences in how the degeneracy is broken.