More narrowband help please!!

[swag72]

Just as I thought, my previous NB image was nothing but an elaborate hoax created by the Gods of AP to lull me into a false sense of security!!

So we have the following data 12 x 1500s Ha and OIII and 11 x 1500s SII. They are being mapped as SHO in order to get the hubble palette. But ............... All I get is yellow. I can not get any blue or cyan to show through at all.

My first thought was that perhaps I'd not changed the filters over but a look at the 3 PI stretched images show that they are indeed different filters. So, is it a case of needing more of one filter? If so, how do I know which it is?

[Uranium235]

Sara, you need to use the levels function in PS to stretch the SII and OIII channels so that the histogram for each channel is roughly the same length as the green. After stretching, you will need to change the black point in r and b becuase that will have shifted a bit. This method increases the noise and is what gives rise to those purple halos you sometimes see, nothing that a bit of NR + desaturate magenta cant sort out though.

All fully explained here:

http://bf-astro.com/hubbleP.htm

Rob

[swag72]

Thanks Rob. Didn't realise I had to stretch the levels!!

[steppenwolf]

Sara, I have had a quick play with your data taken from your first image (hence the small size) and it has come out roughly as expected for a 'turquoise and magenta' implementation of the Hubble Palette. I just followed the original instructions that I gave you a few days ago about balancing the channels as mentioned by Rob above. Here is the image after application of my original workflow - is this more like you had expected? Obviously this is not looking great because of the low resolution data I have worked on but it seems to me that it is heading in the right direction.

[swag72]

That's looking better Steve. I followed the guide you wrote again and also stretched the levels so that they were roughly the same 'depth' - It's turned out much less yellow!!

Sh2-101 (Tulip nebula) in Narrowband by swag72, on Flickr

[steppenwolf]

There you go, Sara, back on the road again!

[Uranium235]

Lovely, a much better looking tulip