Need some help with bicolor processing - link to raw data

[astrovienna]

My bicolors tend to be pretty flat.  Here's a very quick processing (LinearFit, HOO blend in Pixel Math, Masked Stretch, LocalHistEnhance, curves) of Thor's Helmet:

http://www.pbase.com/image/164851957

Nice detail, but colors are very bland.  Most bicolors tend to be much stronger in blue than mine.  5nm Ha, 3nm OIII, both 6 hours.  Any suggestions?  Tweaking the blending hasn't helped much.  Please feel free to work with the linear images:

https://dl.dropboxusercontent.com/u/58468743/Thor_5nmHa_3nmOIII.zip

Thanks for any help.

Kevin

[msmythers]

Kevin

The simplest solution is a luminance mask and curves.

I like to use two tools that are not part of the normal PI distribution. I use a script called ColorMask by Rick S and a module called InterChannelCurves by Carlos M.

ColorMask can be found here. http://pixinsight.com/forum/index.php?topic=7751.0

InterChannelCurves here. http://www.astrophoto.cl/Research.html

You can search the forum for more info. You can find info on how to install scripts and modules here.
http://www.pixinsight.com.ar/en/


Just playing with your image here is something I was able to do using those 2 tools and pixelmath. Not exactly the blue like you are looking for, haha.



Mike

[astrovienna]

Thanks Mike.  I played with ColorMask a bit and I think that would help.  I still need to look into InterChannelCurves.

So is that the way most bicolors are done?  Adjust after the PixelMath blend rather than messing with the blend strengths in PixelMath?

Kevin

[msmythers]

I think bi-color is not so much an exact process. I dabble in it from time to time but I don't actually capture bi-color. As I see it since you only have 2 NB colors you have to take some poetic license in the processing. If it is combined with RGB then that is a different matter. Only the person processing can decide how they want to proceed I think.


Mike

[Geoff]

Maybe a bit off-topic, but there is an interesting take on bicolour images here
http://www.narrowbandimaging.com/synthetic_rgb_page.htm
One of the things discussed is simulating H beta emission by adding about 25% of the Ha into the blue channel.  Both Ha and Hb cover the same regions, but Hb is typically only 25% of the Ha strength.
Geoff

[RickS]

Hi Kevin,

I have done a handful of bi-colour images.  I tend to LinearFit the two NB masters and start with a simple HOO combine and adjust colour afterwards.  That may not work for everyone but it does for me.  I use ColorMask a lot (I wrote it!) and I sometimes use processed versions of the NB masters as masks for additional colour manipulation.  Here's a hint if you want more/richer blues: stretch a copy of your Oiii master and clip the bottom end.  Apply as a mask to your colour image and play around with CurvesTransformation, e.g. boost the blue, boost saturation, reduce red and green, adjust the lightness a little.

I'd have a play with your data if I had a bit more time but I'm getting ready for a trip and I'm already way behind on my queue of data to process.  Good luck!

Here's an example of a bi-colour image based on a simple HOO combine (RGB stars thrown in): http://www.astrobin.com/full/254123/0/

Here's a rather more funky bi-colour where I used PixelMath to adjust the colours based on the brightness of the Ha and Oiii data: http://www.astrobin.com/full/143114/0/

Cheers,
Rick.

[astrovienna]

Here's the final result:

http://www.pbase.com/image/165104436

I found that a saturation stretch in curves followed by a standard SCNR (all with the background masked out) really was all I needed. I did some experimenting with ColorMask, and though I didn't get the results I wanted on this image I can certainly see how useful it is, and I'll be working with it in the future.  Thanks for all the help.

Kevin

[RickS]

Looks good, Kevin!

[oldwexi]

Hallo Kevin!
An excellent result in my personal opinion.

Gerald