Unexpected results in PixInsight

[Droogie 2001]

I am getting a very odd and unexpected result when running the HDRMultiScale Transform process in Pixinsight.

After starting to rework some of my old data I noticed that after a lot of careful previewing the effects of my HDR process differs on a preview window then it does when run upon the main image.
On the below image,  the right hand side is a preview window and produces my desired result. However the left hand image is the result (zoomed in) of the same HDR Transform settings upon the whole image, clearly there is a large difference.
Nothing has changed with the setting and the mask is the same. I am literally running the same process on the main image. I have ensured that I have not inadvertently somehow running the process twice or duplicating a step.

Is this an expected result as it is calculating the entire image as opposed to data on a small Preview window, this does not sound logical at all?

 

Many Thanks

 

 

[Droogie 2001]

Hmm. May have the answer thanks to Harry Astro Shed. It only works properly on a whole image...not previews
Odd that I have not noticed this before!

http://www.harrysastroshed.com/pixinsight/pixinsight video html/pixinsighthomenewbie.html

 

 

[wimvb]

Yes, this is expected behaviour, unfortunately. The process takes its data from the entire image it works on. The input data is therefore different, depending on view. But you can create a preview of the entire image. Just pull the tab on the left side down.

Another process where the result depends on preview/framing is deconvolution, if the preview is small.

[Droogie 2001]

Thanks for the confirmation. Shame as the preview window looks better than when applied to the whole image. Still I understand the reasons why. Good to know about deconvolution too.

[sloz1664]

Yes I've had similar effects on some of my post processing. I now do 3 previews similar to bracketing in photography. One of them works out correct on the processed image ?

I think it is also mentioned in the book Inside Pixinsight.

Steve