FBPP, WBPP, NSG Script

Roger Smith

Hi Adam,

It is not so busy in this forum, so I know my questions won't get lost! I have been away from Pixinsight about 6 - 9 months and getting back now. 

I would like to know your comment about FBPP vs WBPP, ie some guidance about what cannot be achieved in FBPP and when to use WBPP. I read through the release notes. Also, does FBPP work well in a workflow using NSG script weighting?

Several years ago when NSG was in intial development you praised it vs the old Subframe Selector weighting methods in the back then Pixinsight. I have continued to use NSG script as I like the robustness of the weighting, It is fun to use, IMO, and it really shows what is going on in my images (ie gradients, etc, and can improve them.

Does the NSG script offer benefits over the current WBPP and FBPP scripts regarding weighting? I have OSC data. 

Any recommendation where I should dive back in for a review of PreProcessing? I mean which video series?

BTW, what is the status of your own telescope (20"?) installation in Chile? 

Many thanks,

     Roger

BlockHead

Given a large number of frames FBPP can be a great timesavings solution. You can't do anything harmful by not using is..but it can cut down on some time if used. 

Criteria:

1. Many Frames

2. Frames that are most free of *changing* gradients

3. Frames are are free of distortions or other qualities that would make the alignment of images difficult.

#2 is the key reason that LN Normalization isn't necessary and saves time. Normalization also helps rejection- but if you have enough frames his isn't as critical especially in the case of #2 and finally integration under FBPP is done on subsets of data (based the settings you put). As long as these subsets are large enough... (say 20-30 frames) then the quality will be just as good as the Full WBPP treatment. 

NSG requires registered frames as input. But FBPP does not output intermediate frames. So this is not a combination that works. You need to use WBPP to get the registered frames. More importantly using NSG in combination with FBPP is that it defeats the purpose. NSG (like any normalization processing) is NOT fast. 

I just showed a wonderful example in the specialized use of NSG for my latest comet imagery where the normalization files from star aligned data can be applied to comet aligned data. This is very powerful. So yes, there are many cases where NSG is much more powerful than LN implemented natively in PI.

If your frames do not have wildly changing gradients... LN in PixInsight is fine. NSG can give you extra precision- but I have learned people usually do no care so much about this. 

I answer questions on this forum every day. Just 3-4 questions is VERY busy for ONE PERSON. This isn't the PI forum man. Consider it might take me 10-15 minutes to answer. Just like this very question!

To see the current status of the 24-inch (Harris) telescope- visit my Patreon page where I blog as often as I can.  https://www.patreon.com/c/user?u=80004680

-the Blockhead

Roger Smith

Hi Adam,

I appreciate your very clear answers and it really put together the whole picture for my processing direction. 

It was my mistake to look at the Announcements list under Recent Discussions, which goes back to 2019 on one page. I incorrectly assumed this was all the dialogue on your forum. Clearly now there is much, much more. I am sorry for being impolite and rushing to make my comment. 

Best regards,

      Roger