A mellow yellow ic5146

[Ivor]

I took this back in the summer and I've battling with it on and off every since. I'm please with how far I managed to push the data but the image but I don't seem to be able to get the depth I wanted.

One thing clearly stands out is the blue data which for some reason was very weak and has created the yellow star effort.

Please can I have suggestions on how to correct this and also bring out the the nebula and dark lanes?

[MarkS]

Hi Ivor,

This image is already looking promising.

The whole background looks blue to me - remove it by following my instructions saved here:
http://forum.orpington-astronomy.org.uk/index.php?topic=8635.0
Alternatively select a rectangle in the dust lane and use the "black" command to set it to black - this will subtract a constant offset across the image but will not remove any gradient.

To enhance the nebula relative to the stars and to bring out the star colours you need to apply a non-linear stretch.  I thoroughly recommend the IRIS asinh colour stretch:
http://www.astrosurf.com/buil/iris/tutorial1/doc6_us.htm

At this stage you are ready to alter the RGB balance.

You may then want to apply an offset to the whole image to stop the background looking too black.  Experiment using the sliders on the Threshold box or using the Visu command (note that Threshold and Visu don't alter pixel values - they simply alter the way it appears on the screen).

If you don't use IRIS then translate the above instructions into your chosen processing package!

Good luck.

Mark

[Carole]

If you don't use Iris Ivor, you could try the following in photoshop:

Go into levels and click on the middle dropper and then the sky background, to make it blacker. 

Isolate the nebula by drawing a feathered loop around it and increase the saturation. 

Stars are tricky, but you can reduce the yellow by doing select modify/ colour range and highlights, and then a slight modify expand and then feather, and then reduced the saturation, no idea how to put any natrual colour back though I think this has already been lost somehow. 

Carole

[Ivor]

Thanks for the replies having just brought AA5 I've being looking if I can copy your suggestions with this before trying to learn IRIS.

I found a few options and made stab at it combining Carole's levels suggestion



It's a lot better but theres still problems:

The stars are still a touch yellow and there is a clear misalignment in the corners for the blue channel.

I'll replay the steps again to see if I can improve the alignment.