Image processing Halfa

[gianpri]

How to process images Halfa? It should first be calibrated as thought they were all RGB images and then process only the red channel ? Or is it best to first extract the red channel and then calibrate and process only this? Thank
Giovanni

[Zocky]

First you should calibrate and integrate like any other channel. Then you need to combine H-alfa with LRGB. You can do that by using a pixel math or by using a script.

[gianpri]

Thanks Zocky, but I want to get just a gray picture, no color. Why should I combine H-alpha with LRGB ?
Giovanni

[NGC7789]

It sounds like you may be shooting with a DSLR or other color imager. Is that true? Zocky was assuming you wanted to add Ha data to a normal RGB image. If you are shooting with a DSLR you may want to review this thread:

http://pixinsight.com/forum/index.php?topic=5748.0

Your challenge will be what to do with the "wasted" pixels in the G and B channels.

-Josh

[gianpri]

Thanks, Josh. The problem is with the flat field calibration of images Halfa. What I've shown is just what I wanted. I hope.
Giovanni

[NGC7789]

If you have shown anything I cannot see it. Did you include an image?

Please clarify your camera?

As you are talking about extracting channels I will continue to assume you are using a DSLR or other one shot color. In such a case as I understand it you must calibrate before extracting channels as extracting channels imply debayering. It's too late to calibrate after debayering.

Once you have calibrating there are various ways to get Ha data out of a DSLR or one shot color but in all cases you have to give up resolution (there are only so many red pixels) and avoid contributions of noise from the G and B pixels.

-Josh

[Zocky]

Giovanni, like Josh has suggested, please give us some info on your imaging equipment. Than it will be much easier to discuss.

[gianpri]

Forgive my English. I photographed IC 434 with 350D DSLR with filter Astronomic 12nm.Telescopio SW ED80. 14 subframe 480". I had problem to calibrate the lights. Now, following the thread reported by Josh I achieved a good result.

 Thanks
Giovanni

[Zocky]

Is your EOS 350D modified? If not, I would recommend modification, for better H-alfa images.

[gianpri]

Yes, my Canon 350D has been modified with Baader filter. Otherwise you'll be completely blind in Halfa.
giovanni

[Warhen]

alpha, rather than alfa. Ha = H-alpha. :>)