PixInsight Forum

PixInsight => Image Processing Challenges => Topic started by: blinky on 2019 October 27 10:42:41

Title: cant get star align to work on these images....
Post by: blinky on 2019 October 27 10:42:41
I have L, R,G,B Images, that have been stretched - Im trying to align the RGB channels to the L Data but it always fails.  The only way I got it to work was to pick the sub from the stack of L that I used as the ref image and align the RGB to that but don't think its quite right as the red channel then seems to be very slightly off.  Can somebody take a look at the images and tell me why they cant be aligned and is there a way to do it?

I  think this folder should be open to download the data from: https://www.dropbox.com/sh/wi5n87hlxgt73u2/AACF7UXzyhqSQ7mmnUKxx1i6a?dl=0
Title: Re: cant get star align to work on these images....
Post by: dld on 2019 October 27 11:41:25
Hello,

First of all, what version of PI are you using? Are you trying to align stretched images? The norm is to use StarAlignment with linear images. Also I have noticed that you have some stars with flat profiles (saturated stars) and this may be another source of issues.

HTH,
dld
Title: Re: cant get star align to work on these images....
Post by: blinky on 2019 October 27 12:13:08
Hi,

Latest version of PixInsight and yes, Im trying to align stretched images, the saturated stars may well be the issue!
Title: Re: cant get star align to work on these images....
Post by: dld on 2019 October 27 18:15:35
Try aligning the channels before stretching. If you still have problems with the saturated stars and the latest StarAlignment process, please have a look here: https://pixinsight.com/forum/index.php?topic=14056 (https://pixinsight.com/forum/index.php?topic=14056)
Title: Re: cant get star align to work on these images....
Post by: Brad on 2019 October 29 05:34:32
If you are using 1.8.7, there's a new implementation of StarAlignment that uses PSF in the process. Can't remember the exact parameter but it's either part of detection or matching and there's a drop down to turn it off. I found after upgrading that some of my StarAlignment's that worked prior to upgrade were failing until I turned this off.