Author Topic: Any processing tips for a duo band filter with a OSC  (Read 6443 times)

Offline UlteriorModem

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Any processing tips for a duo band filter with a OSC
« on: 2019 November 11 14:26:37 »
Shooting with an ASI1600mc using a ZWO "Duo Band" narrow bandpass filter.

It is a filter that passes Ha and OIII wavelengths and captured on a OSC camera as an RGB image.

Now that is out of the way.....

Looking for tips and hints on how best to handle color balance and anything else that might be usefull.

I watched one on you tube but the guy was using Photoshop, not too helpful for me :D

Thanks in advance.

ps; I hope this is in the right forum section?

Offline pfile

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Re: Any processing tips for a duo band filter with a OSC
« Reply #1 on: 2019 November 11 16:04:20 »
when you look at your debayered files, do you have equal signal in the G and B channels? if so you're really just looking at a pretty standard HOO flow for narrowband processing. in other words if you find some tutorials about how to do HOO with a mono camera, you can just follow those steps from the point at which the RGB image has been created from the H and O masters.

rob

Offline UlteriorModem

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Re: Any processing tips for a duo band filter with a OSC
« Reply #2 on: 2019 November 12 05:49:00 »
I have only worked on one set of images so far in the Cygnus wall. The histogram of the unstretched image has a decided peak in the green channel. Nearly twice as much as the red and blue.

If you unlock the channels and do an STF though it seems to even things out but still has an off color to it.

Offline astroedo

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Re: Any processing tips for a duo band filter with a OSC
« Reply #3 on: 2019 November 12 14:22:05 »
Hi, I suppose that the duo band filter is similar to the L-eNhance by Optolong.
So you have 3 bands on an emissione nebula:

Halpha at 656 nm Red
OIII at   500 nm  Greenish
Hbeta at 486 nm Blueish

You can try using the new "narroband" feature of PhotometricColorCalibration.
Unfortunately the band-pass of the filter is not clear but you can use "average" values to get decent results.

In the attached image you can find the settings that I'm using with th L-eNhance filter, for the ZWO should be the same.

Remember to correctly set the Saturation threshold (It must be lower than the core of a saturated star in your image.

Note: Don't use this filter on a broad band emission object (like a galaxy or a star cluster): it doesn't work properly.
 

Offline chris.bailey

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Re: Any processing tips for a duo band filter with a OSC
« Reply #4 on: 2019 November 14 02:05:23 »
You can use the split CFA Process to get separate channels for each element of the colour matrix. For RGGB, CFA0 will contain the Ha, CFA1 and CFA2 the OIII and CFA3 shouldn't contain too much at all. Now you can combine CFA0 with either one of the OIII channels or an average of the two and then do a Pixelmath Synth for the other. I tend to put CFA0 to red, CFA1 and 2 to blue and do a Pixelmath expression for half of each to green. You will need to play with the colour balance but it works pretty well.