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Ha image - How do I process it?


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I am having a go at Ha imaging this evening with my 12nm Ha filter and my DSLR. My first thoughts are how incredibly difficult it was to focus - Couldn't get anything to show on the screen, had to take pics and get the focus from the 30s images. So a 10 min trial image shows how very red the data is going to come out - My question is how do I process this if I want it just in mono? Do I stack in DSS as per normal and then just do a mono conversion to the data that I assume is still going to be very red?

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Stack and calibrate as normal. Then use Pixinsight or photoshop to extract the red pixels in to a new image - this will give you a lovely mono Ha image, then process as normal

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Stack and calibrate as normal. Then use Pixinsight or photoshop to extract the red pixels in to a new image - this will give you a lovely mono Ha image, then process as normal

Thanks for that John - Can you explain a little more how you go about this - In numpty language of course!!

How do you extract the red pixels?

How do you put them into a new image?

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Open the image in PhotoShop. Select the 'Channels' view, click on the Red channel to select it. Now press CTRL and A to select the whole frame followed by CTRL and C to copy the red channel to the clipboard. Start a new document File - New then press CTRL and V to paste the red channel into this new document. Your new document contains just the 'red' data.

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Excellent Steve - Thank you - Worked a treat on a rather lucklustre image - Back to the drawing board!! Any tips on Ha imaging in particular? Mine is a little uninspiring!!! I also think I missed my target, but it was so damn hard to focus, compose etc as I really could not see anything.

Here's my Ha then from last night. 14 x 1200s lights and that's all. Terrible noise and nothing done on PP other than a quick stretch to pull out the data, I just wanted to see what it was like!!!

post-18339-133877608819_thumb.jpg

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I think you could also use Channel Extraction in Pixinsight. Just untick the G & B channels.

5757392623_66f7826569_z.jpg

Channel Extraction by ashworthacca, on Flickr

Use Channel combination to bring back to a colour from gray.

5757406943_4f2b86ecd1_z.jpg

Channel Combination by ashworthacca, on Flickr

Now.....do you process the gray or colour image before converting to mono:confused:

:D

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Sara, sorry I didn't comment on your image.;)

Focus looks spot on so you did a good job on that one. The data looks to be there to and a little more processing will make it really special for a first HA attempt although it's not too shabby now.:D

Good stuff.:p

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Thanks Martin - Not posted for comments though really, although they are welcome!! - More as a record shot!!

What sort of processing would you suggest Martin - This is all very new to me and I have not tried to process such heavy nebula areas with PI before.

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Thanks Martin - Not posted for comments though really, although they are welcome!! - More as a record shot!!

What sort of processing would you suggest Martin - This is all very new to me and I have not tried to process such heavy nebula areas with PI before.

Unfortunatley I am newer to this than you are so I'm not the one to look to for advice on processing HA images......saying that I would assume that the same principal applies to Ha as to normal RGB image processing, looking to extract detail and contrast in the nebula but keeping the background unclipped and free from noise???

Hopefully the experienced guys will be along shortly to give us some more guidelines.:D

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ok... I guess that's gonna make it much harder, but I meant your not getting the whacked out banding I was getting the last couple of times I tried some long exposures... should have been more specific..

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ok... I guess that's gonna make it much harder, but I meant your not getting the whacked out banding I was getting the last couple of times I tried some long exposures... should have been more specific..

No banding yet - So that's good!!

That's helped the noise levels, thanks Steve.

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Noise Reduction

For this image, I created a duplicate layer Layer - Duplicate Layer and I ran a commercial filter that I have called 'Noise Ninja' to smooth the duplicate layer. Then, from the Layers palette, I selected the new layer and adjusted the opacity

until the original background noise just became apparent.

If you don't have the Noise Ninja plugin then this is the process to use with free software - I've extracted this from the 'reader resources' that go with my book:-

There are several ways of producing a smoothed duplicate; slightly blur a

copy of the original image or use an external noise reduction program

specifically designed to carry out the task of noise reduction. I use two different

programs for this purpose, one called 'Neat Image' and the other called

'Imagenomic Noiseware'.

Start by saving a copy of the image with a different file name in TIF format.

Load the copy image into the noise reduction software of your choice and let it

automatically process your image using the default settings. Once the process has

been carried out, you can click on the image using either program to see a 'before

and after' comparison. However, if the reduction has been overdone using the

default settings, try adjusting the 'Luminance Channel' slider control in the 'Noise

Reduction Amounts' section of Neat Image or the 'Luminance' slider control in

the 'Noise Suppression' section of Noiseware until you get the right amount of

smoothing. You will know if the noise reduction has been overdone as the stars

will tend to run into one another and the image will lose clarity.

Once you are happy with the result, save the image with a new file name.

Open this image in your image processing software, select it, copy it and then

paste it on top of your original image, producing a new layer in the process. If you

are using a PhotoShop plugin, start my creating a duplicate layer and run the

plugin filter on this layer.

Finally, from the Layers palette, select the new layer and adjust the opacity

until the original background noise just becomes apparent and you will have the

best of both worlds, the good detail of the main object but a much 'cleaner'

background.

This process can also be used to good effect to alleviate the 'noise' that

appears in images that have been shot through dampness in the upper

atmosphere.

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