Combining Ha & RGB

[ashworthacca]

Last night I managed 3 hours on the Elephant Trunk Nebula in Ha. Tonight I have another 3 hours worth in RGB although the framing is slightly different. Both nights were imaged with a Canon 1000d.

What is the best way to combine the data from both nights?

Thanks guys

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I am here: http://maps.google.com/maps?ll=53.545096,-1.486935

[ollypenrice]

Have a look at Catatonia's method outlined in his recent E. Trunk image. I haven't tried it but the image is very attractive.

I do it like this;

Process the Ha as usual but then prepare a special version for adding to the RGB. I go for exaggerated contrasts, bright highlights and hard definition of structures in the Ha nebula. I do this because they will be greatly diluted when combined with the red.

You will need to co-register the Ha to the RGB. Registar does this best but it can be done by hand in Ps. Can't remember how, though!

In RGB image, split channels. Copy and paste the Ha onto the red channel and select Blend Mode Lighten in Layers. See what effect this has on the red at 30 to 50% opacity. You can always adjust the brightness of the Ha in Curves by lifting or lowering the middle of the Curve.

Flatten and recombine the RGB. Save.

Now repeat with a higher application of the Ha and see how that looks.

Sometimes the Ha adds good detail but makes everything too red, so you can drop the Ha/red channel in Curves if necessary.

You can allso experiment with addding a bit of Ha to the red in blend mode Normal but this affects star colour.

Lastly, try a little Ha as luminance. I wouldn't go above 15% normally. This is the road to the dreaded pink-with-blue-haloes!

How much Ha to apply is a matter of taste. In the first of these images (using the TEC140) I went for a very light application to keep natural nebula colour and emphasize the spooky look of the Trunk.

In the second (in the Altair Astro 115) I applied more Ha but still less than most people go for. The Ha was much less contrasty in this one, too.

Olly

http://ollypenrice.smugmug.com/Other/Nebulae-and-clusters/i-G5ZPgC6/0/X3/E-TRUNK-HAOSC-X3.jpg

http://ollypenrice.smugmug.com/Other/Nebulae-and-clusters/i-76BpwDM/0/X3/AA115-E-TRUNK-NEB-X3.jpg

PS, For yet another viersion, but using the method above, here's one by Chris Baker using our Tak 85 and his QSI.

http://www.iankingimaging.com/show_image.php?id=220

[ashworthacca]

Olly, many thanks for the superbly detailed reply. I have seen Registar mentioned a few times now and it does look like the ideal tool. I'll have to bite the bullet and buy it I think.

Many thanks Olly

[ashworthacca]

Right, I've purchased Registar but now I'm stuck...when I have my processed Ha & RGB images what do I do to align the images so I can blend them in Photoshop? is there any Registar guides?

Thanks again all.

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I am here: http://maps.google.com/maps?ll=53.544893,-1.487198

[Earl]

Getting this to work with OSC data is making me pull my hair out.

[Glider]

If you stack with DSS then do this;

1...Stack your Ha subs with the first sub set as reference frame, save the resulting file.

2...Now load all of your Red sub files into DSS plus the Ha sub that you just used as reference frame in 1 above. Select all frames. Set the Ha sub as reference frame but then deselect it. Stack the Red subs and save the resulting file.

3... repeat 2 with your Green subs.

4... repeat 2 with your Blue subs.

5... load your stacked Ha, Red, Green, and Blue subs into Photoshop. They will all be aligned with each other by virtue of using the common single Ha sub as reference frame.

[Psychobilly]

Getting this to work with OSC data is making me pull my hair out.

Hi Earl,

I have been looking back through my "links" and here is a page i used to refer to... I Don't know if this will help of Hinder...

Untitled Document

I'll see what others I can dig out from my disorganised list of favourites...

Peter...

[ollypenrice]

Good idea for using DSS there. I hardly use that programme but sometimes it seems ideal.

OK, in Registar you first go to Register Images. If you have the Ha and the RGB open, the active one will be offered as the reference frame. After registration go tp Crop and Pad. DOn't calibrate the images or combine them.

Whn you go into Ps the reistered, cropped, padded image will be a perfect fit onto the other one.

Olly

[ashworthacca]

Glider - that is excellent, I'll give it a try.

Olly - I've just had a play with Registar and managed to get them aligned. Thank you.

[ashworthacca]

Here is the Ha version, RGB and Ha&RGB Combined. I feel like a fish out of water processing the Ha&RGB version.....I will keep at it but at least I got the images aligned.

Elephant Trunk Ha by ashworthacca, on Flickr

Elephant Trunk RGB by ashworthacca, on Flickr

Elephant Trunk Ha & RGB by ashworthacca, on Flickr

Thanks for all the help guys.

[ollypenrice]

Those are good! If you take the Ha Curve in the middle and lift it to brighten it a bit you might get more out of it. Even if you are reaching into the noise when you look just at the Ha, it won't be so bad when the Ha blends with the red.

Olly

[ashworthacca]

Thanks for the help Olly, appreciated.