[Solved] Combing SHO channels from Askar Colour Magic in APP

Mike

I'm not sure how this might have happened, but its probably important to try and sort out the cause. I will say that the only time a similar dimension mismatch happened to me was when I foolishly tried to use lights captured with one set of software with calibration frames from a different set of software.

However, as a short term fix - I would suggest you load the three files as lights (no calibration frames), run register and select save registered frames. You may be able to load the registered frames in the RGB combine tool.

Hope it works.

JC

Thanks John- That seemed like a good idea and I think it's getting me closer to the source of the problem, but I still can't get the combine RGB tool to work.  It seems that APP creates fits output files that are slightly different in dimension when you change the Bayer algorithm from Adaptive Airy Disc to extract Ha or extract OIII.  To check this out, I processed the raw files separately by filter (C1- the dual Ha/OIII) vs (C2-the dual S/OIII).

The raw files have dimension 3840x2160  (from the ASI585MC sensor) 

If I create an Airy Disc file from just the C1 filter, the dimension is 3858x2174    (different from raw image files)

If I extract Ha from the C1 filter, the dimension is 3858x2174  (same as above)

If I extract OIII from the C1 filter, the dimension is 3858x2174 (same as both above and no problem combining them in the Combine RGB Tool)

If I create an Airy Disc file just the C2 filter, the dimension is 3858x2161  (different from C1- this seems to be the problem)

If I extract Ha from the C2 filter, the dimension is 3858x2161  (same as above)

If I extract OIII from the C2 filter, the dimension is 3858x2161 (same as above)

If I create an Airy Disc file using both C1 and C2, the dimension is 3934x2334 (different from everything so far)

If I extract Ha from both the C1 and the C2 filter, the dimension is 3934x2334  (same as above)

If I extract OIII from both the C1 and the C2 filter, the dimension is 3934x2334 (same as above)

Does anyone have any suggestions for how to go from here?  I use mostly default settings in APP.  Is there a way to force the integrated files to be the same size? Or is there a way to change the dimensions of a FITS file?   I think I'm stuck.  Is there another way to use the 2 dual band filters to avoid this problem?

Thank you in advance for your help.

Hi Michael, 

I am not an APP expert, but I think John is right about the registering. I think the file size difference is because of dithering because if you are doing that, all stacked photos from a single night have the same dimensions but the two nights differ from each other because of the dithering. Each night will not dither the same so they end up different. Then you combine both nights together and end up with a third dimension because you are now combining the dithering from both nights. Not a problem-that's just the way it works. So you should be able to load the stacked photos as lights and register them, save the registered photos, and then load those registered photos in the RGB combine. I could be wrong so give it a try and let me know if it works. Good luck.

Tom 

Mike

It was not clear to me that you might be trying to RGB combine data from different integrations - that won't work without reregistering the integrations. As Tom says, different integrations can have different dimensions, but also different star positions (unless both integrations use the same reference frame).

But its an easy fix - just register and save the integrations as I suggested above before using the RGB combine tool. As long as that is the only problem it should work fine.

JC

It worked!  I was holding my breath when I hit the Calculate button, and it popped right up.

Thank you both so much.  I would never have figured that out on my own-- that was a nice Christmas present.  I was starting to think I wouldn't be able to use the S/OIII filter for anything. 

Happy New Year and thanks again.

Mike H.  

You're welcome Mike. Glad to hear it worked.

Tom

Hi @mikehergertyahoo-com, and others that helped here, thanks !

Indeed, the RGB Combine Tool needs data that is perfectly registered. By registering, you ensure that all the stars and other objects in you field of view fit between the layers and that the images have the exact same pixel dimensions.

You can always make a composite using any filter layer/integration, but make sure that you always register the different channels first before loading them into the RGB Combine Tool. You can also include normalization, but the RGB Combine Tool can do that too these days.

Hope all is clear now,

Mabula