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Old 07-06-2014, 08:34 AM
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Narrow band processing? Raw data included if you want to take a shot. Updated.

I'm using pixinsight and I'm trying my first narrow band processing but cant get them to align properly using pixel math. If I select grey scale the images align but not if I choose colour.
I've been following this tute on the Pixinsight forum http://pixinsight.com/forum/index.php?topic=2513.0

Any pointers on to to achieve this.

here are some links to the raw data incase its my data that the issue. There is 5hrs each for Ha SII and OII. The raw data has been calibrated with flats, darks and bias frames.

Registered files here

https://www.dropbox.com/s/cw435iu5ij...-BINNING_1.fit
https://www.dropbox.com/s/8l345s4a5g...-BINNING_1.fit
https://www.dropbox.com/s/9hivvm94uf...-BINNING_1.fit



Thanks
Sandy

Last edited by White Rabbit; 07-06-2014 at 01:33 PM.
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Old 07-06-2014, 09:09 AM
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I think I know what the problem is. When using pixel maths it is stacking the images but not doing a star alignment. So I see the problem but dont know how to fix it.
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Old 07-06-2014, 09:40 AM
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Hi Sandy,
The Files are not registered against the same file. For example Ha's orientation is totally different to SII & OIII.

It would be best if you go back to your registration step and register all individual files (Ha, SII, OIII) against a single reference file. Once that's done you can stack them separately to make the master Ha, Master SII, Master OIII

Regards
Raki
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Old 07-06-2014, 09:48 AM
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For alignment the tool to use in pixinsight is Process>Image Registration>StarAlignment
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Old 07-06-2014, 10:22 AM
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Hi Sandy,

Nice Eta.

Sorry, can't help you with PixInsight, I use CCDStack.

Couldn't help but process the images once I ensured that they could be properly aligned. Lack of clear skies here etc...

Here's what I made of your data.

Cheers
Stuart
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Old 07-06-2014, 10:57 AM
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Ah, that makes sense I did register each filter separately.

I'll re register them.

Thanks
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Old 07-06-2014, 10:58 AM
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Quote:
Originally Posted by rat156 View Post
Hi Sandy,

Nice Eta.

Sorry, can't help you with PixInsight, I use CCDStack.

Couldn't help but process the images once I ensured that they could be properly aligned. Lack of clear skies here etc...

Here's what I made of your data.

Cheers
Stuart
Wow, that looks really good. Thanks it gives me something to strive for.

Cheers.
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Old 07-06-2014, 11:54 AM
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Oooo yes please!
Always happy for new data to practise with
Will give it a go with AstroArt v5 tonight, gotta do the family thing today.
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Old 07-06-2014, 12:15 PM
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The new images have been uploaded.

Last edited by White Rabbit; 07-06-2014 at 01:33 PM.
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Old 07-06-2014, 02:02 PM
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Stuart, now that I've had a chance to play around with the images, your image is all the more impressive.

Would you mind explaining the process you went through? I particular the pallet you used, I'm not overly fond of the the Hubble colour set, I like the colours in yours.

Thanks
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Old 07-06-2014, 03:47 PM
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Hi Sandy,

No problemo, it's basically the same as the workflow here.

Anyway, I use CCDStack to align the images and, more importantly, once aligned they can be normalised. This usually (though not always) fixes the colour cast in the background. First image.

I then colour combine the images according to the HST palette, i.e SII-Red, Ha-Green and OIII-Blue. Maybe tweak the exposure here with a bit of DDP, then save at 16 bit tiff file for export into Photoshop. In your case I also made a master luminance from addition of the three colour exposures using a maximum combine, again, saved this as 16 bit tiff for Photoshop.

Once both files are open in PS I then colour balance the RHS of the histogram of the colour image, usually this means knocking off some of the green intensity as Ha usually dominates NB nebula images (again, not always). The Luminance channel get a bit of sharpening of the image excluding the stars, standard fodder here, though sharpening is a personal preference, I like sharp images, so tend to over sharpen them according to most people 'round here.

Now, working with the colour image, bring up the Hue/Saturation adjustment and desaturate all the magenta, you can experiment with the range of magenta/violet to knock out, this removes the violet stars and halos from the image, but really screws the star colours, if you want proper coloured stars, then you should do a short exposure RGB imaging run for the stars. Virtually none of the nebula will be this colour, so knock it out completely. Image 2

Now, go through the selective colour regime listed in the website I referenced, I have made a PS action to do this automatically, this shifts the colour palette to the more "golden" hues and enhances the blues. Image 3

Combine this image with the luminance in the usual manner, the image will wash out the colours, so I use a couple of methods to bring those back. The first one involves duplicating the colour layer in PS, then converting it to a Multiply layer between the Luminance (Background) layer and the colour layer, you then vary the opacity value of this layer to get the desired effect. Or, you can use Louie Atalas' method of duplicating the LRGB image, changing the blend mode to Soft Light and then varying the opacity of this layer. I use a combination of both as I find that each works in a slightly different way. Image 4

Lastly, combine all the layers and save as a psd file and import into Lightroom, use the clarity and vibrance sliders to your own liking.

Hope this helps.

Cheers
Stuart
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  #12  
Old 08-06-2014, 06:54 AM
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Thanks for the link Stuart, very helpful as is your examples.

I'll have more of a play today and see what I come up with.

Cheers
Sandy
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Old 09-06-2014, 09:24 PM
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I had a bit of a play around with it, it's still not right I've crushed the highlights in the blue channel. It'll need a rework.

Thanks
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Old 11-06-2014, 04:00 PM
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I was keen to have a play with your data, but getting invalid link errors on the dropbox links.
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