Another go at the Trifid.

[tilbrook@rbe.ne]

Hi,

Thought I'd try some reprocessing on the Trifid. I've learned a few more processing skills from my first attempt earlier this year.
One technique that seems to work quite well for reducing gradient by Rob Pollard
Gradient Removal (http://www.ccdastro.pwp.blueyonder.co.uk/gradient_removal.htm)

This is for PS (http://www.astronomyforum.net/wiki/PS) 7 the version I'm using, I applied the process to my image and it's sure enhanced the nebulosity, reduced some of the gradient and gives a more pleasing back ground.

I'll be trying it on some other images.

Cheers,

Justin.

[David Fitz-Henr]

Nice work Justin - you have brought out some good colours in this. It would be interesting to see it next to your original attempt.

[Stevec35]

Nice shot with good colour Justin but I think you have smoothed it a bit too much. Some of the fine detail looks washed out.

Cheers

Steve

[gregbradley]

Not sure if the offset option is available on your version of PS. If it is increase that to 20 or 30 otherwise you tend to black clip the background.

The background seems slightly mottled. Have you used the minimum filter at some point?

The blue neb is too magenta. I would use selective colour and get some cyan back into the blues and reduce the magentas.

Greg.

[tilbrook@rbe.ne]

Thanks for the tips Greg!

Yes your right, I did use the minimum filter set 25% might try a bit less.



Thanks Steve!

I have over processed a tad, trying to bring out the blue nebulosity around the trifid. I over compensated by blurring and smoothing.



Thanks David!

Here's the link to the original image.
http://www.iceinspace.com.au/forum/attachment_browse.php?a=113729

Cheers,

Justin.

[Ross G]

Great looking Trifid photo Justin.

You have captured so much detail.

Ross.

[gregbradley]

[QUOTE=tilbrook@rbe.ne;886059]Thanks for the tips Greg!

Yes your right, I did use the minimum filter set 25% might try a bit less.


My opinion is not use the minimum filter at all. There are other ways to achieve smaller stars or sharpening that are not destructive like the Minimum filter seems to be. Its one of Photoshop's least valuable tools.
I've wrecked quite a few of my own images in the past using that trying to get over elongated or overly large star sizes.

Greg.

[Stevec35]

There is a way that does make the minimum filter a bit more effective:

- Duplicate the image
- select the stars (select - color range). Basically you select the stars you
are primarily interested in minimizing.
- If you select part of the nebula just delete it from the selection
- Expand selection about 5 pixels
- Feather about 2-3 pixels
- Add a layer mask
- Gaussian blur the layer mask with a radius of about 2.5 - 3
- Apply the minimum filter (radius 1-2) pixels.
- Adjust opacity to get natural looking stars

This works far better than the raw minimum filter. I agree with Greg - used by itself it's pretty useless.

Cheers

Steve

[tilbrook@rbe.ne]

[QUOTE=gregbradley;886191]

Thanks Greg,

Looks like I need to put a no go sticker on this function.




Thanks Ross!



Thanks for taking the time to list the procedure Steve!

Cheers,

Justin.