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Questions about color into a mono HA image

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9 replies to this topic

#1 Star Slinger

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Posted 22 November 2019 - 10:23 AM

Hi there...

 

New to narrowband imaging so this might sound like a dumb question, but went out and took a few lights and darks of the Heart Nebula last night.

 

I only used my HA filter on a mono camera. Is there a way to make the nebula red? Doesn't HA give off red light...or would I have had to have taken a few frames with my RGB filters to plug the red in? I'm a little confused as to how this works.....I'm over playing with black and white photos and want to start learning how to add color. Thanks in advance. 

 

 

 

 



#2 sink45ny

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Posted 22 November 2019 - 10:41 AM

Sure you can make all the illumination red but I doubt that would make a pleasing image. Capturing Oiii (oxygen) & Sii (sulfer) along with Ha is (usually) the way I create a narrowband image.

Some examples are below, click the images for full details.

 

Here's an example of a Bi-color narrownband image.

get.jpg?insecure

 

Here's an example of a Tri-color narrownband image.

get.jpg?insecure

 

Here's an example of a Ha Only narrownband image. I worked for an hour to remove the stars change them to white and re-add them and I am not too happy with the result. If the stars weren't changed to white it would look even worse.

get.jpg?insecure

 

And one more Ha Only image left as B&W.

get.jpg?insecure


Edited by sink45ny, 22 November 2019 - 10:45 AM.


#3 Astrola72

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Posted 22 November 2019 - 10:45 AM

Steve just beat me to this. You've got the filters - why not gather some O3 ans S2 data and have fun with the Hubble (or related) palette? Converting to red would still be monochrome, and really less interesting than the grayscale. IMHO.

 

Joe


Edited by Astrola72, 22 November 2019 - 10:45 AM.

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#4 sink45ny

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Posted 22 November 2019 - 10:54 AM

BTW Star Slinger here's a good link for Hubble Palette imaging if you aren't already familiar with it - https://www.lightvor...le-palette.html


Edited by sink45ny, 22 November 2019 - 10:55 AM.


#5 bobzeq25

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Posted 22 November 2019 - 11:04 AM

Taking a different tack here, and answering the original question.

 

It's easy to convert an Ha image to red.  You just load the stack into the red channel (how varies by processing program, in PixInsight you do an RGBCombination with Ha as red, and blue and green left blank).  Done.

 

But I think you lose some of the appearance of detail by doing so.  I'd say that's clearly true.  Probably something to do with the fact that your eyes see detail better in black and white.

 

In addition to that, I think black and white is more aesthetically pleasant.  Which is a taste thing.  But I certainly agree with sink45ny about red stars.  Fixing that is _not_ easy.

 

Bottom line is that few imagers change Ha data to red.  But, you are of course free to do what you personally prefer.


Edited by bobzeq25, 22 November 2019 - 11:26 AM.


#6 Benni123456

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Posted 22 November 2019 - 11:26 AM

I would suggest pixinsight.

 

Do not do luminance, only R,G,B, Ha and OII. The narrowband usually with longer exposure, say twice or 3 times the exposure of the r,g,b.

Then get pixinsight. There is an rgb combination process. After that, use either the NBrgbcombination script from pixinsight or the pixinsight emission line integration script which you can download here:

https://www.skypixel...ht_scripts.html

 

Usually, either the NBrgbcombination or the emission line integration script will give you a pleasent result

 



#7 Der_Pit

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Posted 23 November 2019 - 08:04 AM

I had the same issue/question a few days ago and Brian pointed me to this thread

 

From there I especially liked the suggestion of Frank (freestar8n) to put a 1/3 intensity copy of the Hα data into the blue channel to represent Hβ.  It still is one color only, but the result (for me) is somewhat more pleasing to the eye than the pure red version.

 

It's also very helpful to use StarNet to first remove the stars, colorize the nebulosity and re-combine again with the (white) stars.  Those kind of processing I usually do in GIMP.



#8 schmeah

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Posted 23 November 2019 - 09:33 AM

Yes, in fact you can pretty much create any colors you want in a monochrome image. Interesting that there have been several new threads on this topic lately. Here is one that I started with an example of an approximation of a color narrowband image of NGC 281 using only an  Ha filter:

https://www.cloudyni...-image-ngc-281/

 

Keep in mind that the detail from the Ha filter is real. Everything else is fake. While it’s something fun to play with for a while, you will want to get more filters. One thing this type of playing around may do, however, is teach you how to accentuate limited data in weaker emission lines, ie: the OIII and SII relative the Ha.

 

Derek


Edited by schmeah, 23 November 2019 - 09:40 AM.

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#9 MapleEve

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Posted 24 November 2019 - 08:45 AM

Sure you can make all the illumination red but I doubt that would make a pleasing image. Capturing Oiii (oxygen) & Sii (sulfer) along with Ha is (usually) the way I create a narrowband image.
Some examples are below, click the images for full details.
 
Here's an example of a Bi-color narrownband image.
get.jpg?insecure
 
Here's an example of a Tri-color narrownband image.
get.jpg?insecure
 
Here's an example of a Ha Only narrownband image. I worked for an hour to remove the stars change them to white and re-add them and I am not too happy with the result. If the stars weren't changed to white it would look even worse.
get.jpg?insecure
 
And one more Ha Only image left as B&W.
get.jpg?insecure


Have seen huge halos on Chroma LRGH in Pleades, is that normal? Since Astrodon can handle the halo well.

#10 sink45ny

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Posted 24 November 2019 - 09:30 AM

Have seen huge halos on Chroma LRGH in Pleades, is that normal? Since Astrodon can handle the halo well.

Show me examples where AD handles the halos well please.

 

Example looks like halos to me - https://astrob.in/63096/0/


Edited by sink45ny, 24 November 2019 - 09:43 AM.



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