weightImage

Pawel Kolano

Hi,

My stacked image looks all good, but when opening the stack there is an image you can see below.

https://ibb.co/9cH308G

I've never seen it before and wondering if there is any issue?

Thanks

BlockHead

Drizzle is a funny algorithm. The map is supposed to show you the density of drizzled information (and whether there are "holes" due to the fact there isn't enough information (not enough files to begin with).

Are you certain you want/need to be drizzling 2x?

There is certainly a correlated effect that might not be optimal..but I really do not know.

-the Blockhead

Pawel Kolano

Well I would prefer to drizzle 2x to get higher resolution to future proof it, if that makes sense.

I dither every 3-4 frames, and the image was 107x120s.

BlockHead

Certainly sounds reasonable in terms of number of frames. I would, however, dither each frame. I do not understand why people do not do this. I am not saying this is it..but dither algorithms can make patterns.

Whether you are benefitting in terms of resolution is a different question. This usually requires a very careful analysis.

-the Blockhead

Pawel Kolano

Thanks, I'm new to dithering and was told by a friend to do it each 3-4 frames, since it takes time.

If I uploaded the stack would you be able to tell if anything is wrong?

I just did NGC1499 last night and had the same weightImage.

Cheers

Pawel Kolano

I've tried drizzle 1x and the weightImage looks all green, but the stars look way worse.

Pawel Kolano

It seems like the issue is the pedestal set in WBPP.

Previously I would set pedestal to 100 as you recommended in your older video, and there wasn't any zero value pixels, but the weightImage doesn't look uniform.

If I set pedestal to auto it's choosing pedestal between 35-50 and there are some clipped pixels, but weightImage looks uniform.

I did post some images here:

https://pixinsight.com/forum/index.php?threads/dbe-spitting-out-stretched-image.24313/page-2#post-159072

Do you have any suggestions on how to find out best pedestal setting please?

BlockHead

I didn't recommend 100. I recommended a value that will always be large enough. 

The automatic pedestal that is now available is fine. The difference between 35 or 50 is negligible.

You believe that the pedestal has something to do with the results of the weights image. I don't think so... but this isn't something I have investigated. 

-the Blockhead