Weighting images after registration and generating drizzle data via registration


Jul 9, 2019
Not sure if I am missing something, but following Rogelio Bernal Andreo's book Mastering PixInsight the recommended time to weight images is after aligning them. This of course, is also where the initial drizzle data is created. However, I found out that if you weight the images after registration and initial drizzle data the file names will be different by the default postfix _a. Same for creating L. Normal data after weighting as well. It seems the initial drizzle data is linked to the initial file name from which it is generated from, same for the L. Normal files.

The only work around I can think of is to avoid changing the name in any manner once you register and drizzle your images initially, same for creating the L. Normal data after weighting.

Am I missing something? Seems if weighting after registration is the way to go (it makes sense) then is there way to do so without having to avoid changing the file names?

Or, does it really matter if you weight prior to registration?

Juan Conejero

PixInsight Staff
Sep 2, 2004
Valencia, Spain
Image weights should normally be calculated from calibrated raw data, that is, before image registration. This is because registration applies interpolation, which acts like a low-pass filter by correlating neighbor pixels. So the conflicts that you are describing with drizzle data files should not exist if good practices are implemented.