Good method for using Ha in Luminance channel?

[topboxman]

What's a good method for using Ha in Luminance channel? I have seen people use Ha images instead of Luminance images and use Ha as a Luminance to apply to RGB. I found tutorials for adding Ha to Red for red channel but cannot find tutorials for using Ha as a Luminance.

Thanks,
Peter

[cfranks]

There is a good tutorial from the famous Harry!  http://www.harrysastroshed.com/Hagalaxy.html

Charles

[topboxman]

I have seen all of Harry's tutorial. Correct me if I'm wrong since I am deaf and cannot hear the narration but I don't think his video shows how to use Ha in Luminance channel. His video showed how to combine Ha and Red and apply them to red channel. I am asking how to apply Ha to Luminance channel like this:

L = Ha
R = Red
G = Green
B = Blue

Are there any tips or tricks like magic Pixel Math formula?

Thanks,
Peter

[Harry page]

Hi

You can just use the LRGB combimation tool -- but this will just use the Ha as a lumince so not all Ha images will be suitable

Harry

[topboxman]

Hi Harry,

Glad to see it's simple. I think once I did something like that but it resulted horribly looking colors. I am not sure what I did. I will have to go back and try it again.

Thanks,
Peter

[topboxman]

Harry,

Does your tutorial about adding Ha to a Galaxy work well for emission nebulae like Bubble Nebula? I made a great Ha image of Bubble Nebula. I am having difficulty including Ha with RGB of Bubble Nebula.

I just migrated from SXVR-M25C OSC to Atik 460EX mono with LRGB, Ha, Oiii and Sii filters. My first image with a new camera and equipment was Bubble Nebula. I think I used too long exposures on LRGB because there were lots of LP gradients and didn't seem to work well with a nice Ha of Bubble Nebula. I also think the seeing condition was less than ideal. You can see my Ha-Oiii-Oiii bi-color of Bubble Nebula at:

http://tinyurl.com/Bubble-Nebula-Bi-color

The first image is bi-color, second is Ha and third is Oiii. I think the seeing condition was bad when I imaged Oiii of Bubble Nebula. I have not yet uploaded LRGB of Bubble Nebula.

Peter

[Harry page]

Hi

Yes works well 

Here is my go inc Ha  http://www.harrysastroshed.com/Image%20html/bubble2011.html

Harry

[topboxman]

Very nice image of your Bubble.

I must be doing something wrong. I followed your instruction and the star colors appear to be wrong. Most stars are blue. I will go back and try again.

Do I need to combine RGB first, then split into separate RGB, then follow your instruction and do RGB combination again?

I didn't initially do RGB combination. I followed your instruction using calibrated and stacked Red and Ha images and then RGB combination. Is there a difference?

Thanks,
Peter

[topboxman]

I tried it again and still get blue stars. I think I know why. The stars in Ha image are quite a bit smaller than in RGB images. The larger stars in RGB may create halos around smaller stars of Ha image. I believe the stars are bigger in RGB images probably due to sub-exposures being too long, the seeing condition was bad or a combination of both. The red nebulosity in Bubble Nebula looks good.

If I process only RGB and not include Ha, then I get nice star colors.

Someone from Cloudy Nights forum suggested to remove the stars from Ha image before blending to Red image to avoid nasty halos. Anyone know how to remove the stars from an image? Can it be done with Star Mask? If so, how?

Thanks,
Peter

[topboxman]

I ended up applying Ha as Luminance to RGB and worked pretty well.

When I first applied Ha as luminance to RGB, the nebulosity was pink. It took me a while to figure out how to tweak the colors. I can't find PixInsight tutorials related to applying Ha as luminance to RGB. I hope I did it correctly. I had to play around with the weighting (0.300), lightness (0.450) and saturation (0.400) when applying Ha as Luminance to RGB for LRGB combination.

I think I need to re-capture RGB since the stars were quite bloated due to bad seeing condition. Toward the end of imaging, the PHD RMS was increasing because the guide star was bloating and getting dimmer.

This is my first time owning a mono camera (Atik 460EX) with filters and I find it pretty powerful over my old SXVR-M25C OSC camera I used for three years.

Peter

[topboxman]

I think I finally figured out how to add Ha to R. After adding Ha to R using PixInsight script, I didn't set the background boundary limits correctly in Background Neutralization and Color Calibration. With proper settings, the star colors look much better.

I still have a long way to go but I am getting the hang of processing with Ha and RGB.

http://peternagy.smugmug.com/Telescopes/Nebulae/15823498_3vBdTQ#!i=2099824883&k=cjWhMxF

I can't believe this was taken under heavy light pollution.

Peter

[Ioannis Ioannou]

Hi Peter,

I did not followed the forum close so I missed your questions (and the same at CN). I guess you have already found this script and used it?

The issue has been discussed long on this forum, how you add narrowband data to RGB data and what is "proper".
The script (and Harry's totorial) adds Ha to R, based on Vicent's method. But adding to L it is a different story. R contains Ha, and the method tries to join them based on logical assumptions. But how you join Ha to L without straggling the other colors ? (replacing L with Ha is even worse). Personally I have done this once, on this photo, but in order to do this I

1) used the script to make a HaR-G-B,
2) linear fitted L with Ha and joined them with a percentage (I think I used 20% Ha or something)
3) then joined all to LHa-HaR-G-B

just my 2 cents

[topboxman]

It was more like operator error on my part when I was using Silver Cup's script and now I think I got it right. It's my first time ever using mono camera with RGB and NB filters so I didn't know what to expect. I was doing all kinds of experiments. Before that, I was using SXVR-M25C OSC camera for three years.

Thanks for providing useful tips.

Peter