Make a bi colour narrowband image

[Astroblagger]

can someone point me in the direction of a tutorial to do this im having getting a final result.

[tingting44]

this might be of use if you use PI

http://lightvortexastronomy.blogspot.co.uk/2013/03/tutorial-nebulae-pixinsight-guide-for.html

[Astroblagger]

Sorry don't have PI.

[ChrisLX200]

Sorry don't have PI.

What do you have?

ChrisH

[Astroblagger]

I got 1 hour of Ha and 1 hour 10 mins OIII on the pelican, with a 200mm F2.8 lens and atik 314 can't seem to get that blue colour I see in other peoples images.

[swag72]

What processing software are you using? I find I do almost all of mine in the colour select tool in PS

[MartinB]

The easiest and sometimes the best way, for me anyway, is to use your OIII for both the blue and the green channels.  Just open up your OIII and Ha images (they will need to be aligned, exactly the same size and greyscale).  Make a duplicate of the OIII.  Then, under channels, choose merge channels, select RGB.  Select Ha for red, OIII for green and the copy for blue.  That gives you a starter for 10.  The luminence depends on how much unique data there is in the 2 different filtered images.  If the OIII carries little extra detail and is just adding colour at the right place then create a luminence using the Ha.

There's quite a lot of processing work around using the different colour tools in PS to get the colour right.  One problem when you add the luminence is that the nice deep Ha red becomes a salmon pink.  To reduce this, with the Ha/OIII/OIII colour image try leaving the black point on the histogram a little over to the right after the final stretch.  Then duplicate the layer and select soft light as the blend mode.  Paste on the luminence using lighten as the blend mode and pull back the opacity a little.

It's not possible to give an exact, step by step, routine because it varies depending on the type of data you have and the target.

[Astroblagger]

Iv got photoshop cs3, I got loads of Ha signal not so strong on OIII, but will try your technique as described. Thanks.

[MartinB]

You will need to stretch the OIII data more than the Ha to get that band to show.  Then you have to deal with the problems that  creates for the star colour!