1.081 Neutralize-BG

I check disabling neutralizeBG in 5)normalize, and the result is ok

NeutralizeBg in view after mosaic composition is ok and i can go ahead with light pollution correction

There is also a tooltip, when you hover over that option in tab 5, mentioning that you’d need to calibrate the background later on. What happens when you turn off a similar option on the right for the preview window? I think it might be a data issue in this case, preventing it from working normally.

I have a similar issue in 1.082.  Integration proceeded normally and the view of the image was very good.  When I selected the tool, normalise background, the whole image went white in a very similar way and I could not correct the picture.  Image pixels were all scaled to 0.9999xxx or similar.

Screenshot with example of "white out". Getting this issue regularly.

I will ask Mabula why this exactly happens, I think it must be data related otherwise many more would have it. I'll come back to it asap.

I've been having this white-out too, every now and then. When viewing in registered mode, stepping through the individual exposures after alignement, this happens for a few of the exposures, not for all.

Mabula also thinks this usually happens when there is a calibration data issue. If you have the specific data, I can give it a look.

Hi Vincent, sorry for late reply

As stated by Ralph Snel, this "white-out" issue happen quite often, not always in the same module, and seems to me an issue in the viewer and not in the real data processing.

Here two more cases with latest APP 1.082, if you need i can send the raw data

Wide field mosaic

In calibrate star colors module, depending on selected areas number and poosition, the preview go all white, but APP il still able to calculate the star color graph.

2 areas: whiteout

3&4 areas: ok

5 areas: whiteout

Veil nebula

Two different session at iso3200 and iso6400 processed completely indipendently (different light, bias, flat, dark)

Exact the same processing sequence, advanced normalization with neutrilizeBG enabled.

ISO3200: all ok

ISO6400: when i select neutralize-BG in viewer after 6-integration, i have white-out.

Combination of the two integration: all is ok with neutralizeBG selected in viewer, reinforce the possibility that is a bug in the viewer.

I don't think it's a view issue as that would have popped up a lot more if so. But I'd like to have a closer look at the data for sure, if there is some issue specific with this data and we can solve that, we will.

Go to https://upload.astropixelprocessor.com and use upload1 (or upload2 till 5) as username and password will then be the same as the username.

Create a directory named “fendium-whiteout” and upload in there. Thank you!

Hi there,

I see you created a folder, but there is no data in it. Is that correct?

Posted by: @vincent-mod

Hi there,

I see you created a folder, but there is no data in it. Is that correct?

yes i have some connection problem, i will notify when the upload is completed

Hi Vincent

The upload is completed, in the folder fendium_whiteout you can find the raw files related to my last post: Velo Nebula and Wide field Mosaic.

Bias and dark are common since i use the same sensor (Canon EOS6D) while the flat are specific for each session, due to different lens setup.

Thank you.

Cheers! Will download it today and have a look.

Ok, finally onto your data. I'm guessing you normally have more bias frames for instance then the ones you uploaded right?

I'm afraid I couldn't trigger the whiteout issue in 1.083-beta1. I am wondering about a few things though. ISO6400 (or maybe even 3200) is very high and usually not beneficial for the sensor you're using. There is always an optimum of signal/noise ratio with a given sensor. Here's a very nice overview for DSLR's: https://dslr-astrophotography.com/iso-dslr-astrophotography/

There are possibilities of these kind of issues when calibration has an issue. And since it's happening only with the 6400 data, that might be the case. Combining it with the 3200 may solve something, as the 3200 data doesn't have the issue. There might be something going on like a wrong calibration of the noise floor in the data, APP then corrects it in a wrong way. That would not be a bug, but a data issue. What exactly the issue is is difficult for me to see here. Maybe you could try to integrate the 6400 data without any calibration files and see if it still triggers the issue?

Hi Vincent sorry for late reply

For now this is all bias frames i have, i know is not optimal and i plan to do more, but i have uploaded exactly all frames i use for my processing.

Yes iso 3200 and 6400 is probably too high and the optimum is around 1600, i was using 800 and seems too low so i decide to increase. I was not aware of that this analysis was already made and result available online, so tankyou for sharing, i will probably switch and stay with ISO1600 for the future. I can understand that with such high iso the calibration an integration of many light frame might end in a wrong result, probably when there are multiplication and division of values that can generate overflow or underflow of data. I will try to integrate the 6400 data without any calibration and see the result.

Anyway, this do not explain when whiteout appear AFTER the calibration and integration as for the "Wide Field Mosaic" that i have uploaded. In this case i think all the integration and calibration are over, and APP work on a single FITS image. Sometimes, depending on selected areas, the image becomes whiteout while the data underneath seems ok. In wide field mosaic i was doing csc, and despite the image whiteout, the stars data are present.

It just happen again today during a lpc on M11 target: the small area in the right bottom corner cause the preview go all white, but the correction model seems ok. I can save the image and open in other SW (fitsviewer for example) the image is present and ok. The problem is the APP DPP autostretch that sometimes autoselect the wrong values that cause the preview to whiteout. In this case the only way to restore the image is to set manually B/W/ST values; is very annoing because just a few pixel difference in selected areas can trigger this situation.

Yes, that is strange, but my gut feeling is that it has to do with the background noise level. That's why I pointed to trying it without calibration frames to see if they cause an issue like that.