Ngc 6752

[PRejto]

I've been doing so much testing that I've hardly imaged at all for a long time. So much so that I've forgotten how to process. Not to mention that I decided to bite the bullet and get PixInSight. I must thank Mark Adams for being so patient and for helping me to get going with this program as I put up quite a fuss. Change is hard!! This image used 3 programs: CCDStack, PixInSight, and Photoshop CS-5. I did the initial colour combine and background fixes in PixInSight...in other words all the linear steps. I was happy with that but have too much to learn to go any further!

Anyway, this is the result of a test of a TAK TOA-67 flattener on my TEC180. It has a nice long BF so I'm going to be able to just squeeze my ONAG XT in. This was without the ONAG. The image is cropped some only to control the background and not because of star shape.

TEC180
TAK TOA-67 Flattener
Moravian G2-8300
Astronomik LRGB

Lum 12 x 3 min
RGB 9:9:12 x 3 min

Processed in CCDStack, PixInSight, Photoshop CS-5


New Version:

Full Size http://www.pbase.com/image/161014066

Small: http://www.pbase.com/prejto/image/161014066/large

Thanks for looking!

[gregbradley]

Yeah Peter, you took the plunge, good on you. A terrific image. Love the round tight stars. Perhaps a bit of background colour noise. Its slight.

Greg.

[PRejto]

Hi Greg, Thanks. I see it too but I'm not sure of the best way to get rid of it. I tried to "bury" it but then I started to clip the image. What would you do?

Thanks!
Peter

[topheart]

Very nice!
Tim

[strongmanmike]

Good to see this glob getting some attention lately, this is a really nice version too Pete. For some strange reason I can't actually open the pbase files at the moment (at work) but the IIS attached file still looks good.

Mike

[PRejto]

Thanks Mike. I think Pbase is having some trouble today. Images were opening erratically at times.

Peter

[Octane]

That looks awesome, Peter!

Beautiful colours.

H

[Octane]

If you wish to smooth the background, go back to PixInsight and use the MultiscaleMedianTransform on the background. Create a mask to protect the stars first. :)

H

[PRejto]

Haha, I don't have a clue how to make and apply a mask in Pix. Now in Photoshop I could do that easily. Can I apply the tool in Pix and then do the mask in Photoshop on a copy of the image?

Thanks for the tip!

Peter

[Octane]

Absolutely!

But, to make a mask of your image (in linear mode):

Right-click on the image and select "Duplicate".

Now, bring up the STF tool and press Ctrl+A to apply an autostretch to the duplicate image.

Bring up the HistogramTransformation Tool. Drag the little diagonal (apply button) from the STF tool to the base of the HT tool; it will now show you the STF curve.

On the STF tool, press the disable STF button and apply the HT to the duplicate image.

Next, either extract the luminance from the image or convert it to greyscale.

Once you've done that, go back to your original image, right-click and select Mask, then choose the luminance/greyscale image as the mask. :D

You will likely need to invert the mask, so press Ctrl+I to invert it to protect the stars (red areas are protected).

Now that the mask is in place, press Ctrl+K to hide/show it, you can run the MultiscaleMedianTransform tool and it will only apply to the background.

Let me know if this doesn't help. :)

H

[Placidus]

Peter, that's exquisite. Beautiful colour.

I had a look at the histogram and the noise. There's almost nothing there to clean up - it's a great image - but what there is is easily removed with a wavelet filter, with negligible impact on the stars. Personally I think there' nothing to fix.

Best,
Mike

[Regulus]

That's a beautiful field of colour Peter. A really nice globular photo.

Trev

[codemonkey]

If you only viewed the thumbnail here you might write this off as I almost did (globs don't tend to excite me much), but after viewing it, that's actually really nice; good work! Almost tempted to look at some globs myself after seeing this.

[PRejto]

Thank you ALL for the nice and very helpful comments! And, H. for the Pix lesson! I'll give it a go.

Mike, I met you last week at the Imaging Group" and I asked you about the guide camera PA and if there was any logical reason why having the PA not set to a cardinal PA would make any difference. Thank you for confirming my initial reasoning about that! And, see you and Trish at the next meeting.

Peter

[Rex]

Lovely image Peter. Tight stars and nice colour. Top job mate.

[Frostyricho]

spectacular, hoping i can do images like this one day:rofl:

[gregbradley]

In Photoshop make a star mask (as simple as colour range tool, select highlights and it will pick up most stars. Then expand the selection a little until the whole star is covered and a tad more then feather 1 pixel).

Apply the mask to the image. Use a noise reduction routine on the background - Noise Ninja. There are several available noise reduction tools on the market.

Remove the mask.

Its a great image and this is a minor touch up point.

Greg.

[PRejto]

Thanks Rex and Richo for your kind words! Much appreciated.

Greg, Unfortunately what you see in my first version was with Noise Ninja already applied. I finally resorted to a mild desat of the background + a .5 pix blur. I think it's a little better. On most of my monitors it looks OK. On one very critical monitor I still see a splotchy greenish pattern. I suppose I could turn desat all the way down. Is that cheating?

H. I tried the MMT tool but it didn't seem to do much to the background. I'm sure I just don't know what settings to play with (yet). My days using PixInSight are very limited. I need time and today I just wanted it "better!"

Thanks all. Appreciate hearing if the new version is moving in the right direction.

Peter

PS New version in first post.

[gregbradley]

The new version looks very good.

Greg.

[Octane]

Pete, if you like, I'm happy to have a play with your FIT image and have a go at the background? Will also document my steps so you can try yourself.

H

[PRejto]

Thanks!! Look forward to seeing how you do it in Pix!

Peter

https://dl.dropboxusercontent.com/u/110452899/NGC6752_LRGB.tif

[Octane]

Before and after, Pete.

Background, flattened.

H

[PRejto]

H!

That looks good! Are you going to share the secrets?

Thanks so much.

Peter

[Octane]

I'll write in the morning. I woke up as I wasn't feeling well and thought I'd have a play.

That was literally 1 minute of work, after 2 minutes of experimentation on a preview. :)

I don't have a DropBox, but, I'll upload the final TIFF for you on my webspace for you to further play with.

H

[Paul Haese]

Peter, the resolution is great. So too is the star colour. I really like the overall look of the image.

There is indeed some noise in the background but you could simply collect more data rather than trying to process out the noise. Noise control really ought to be the last resort. A couple more hours would give you the noise control you would need.

There is also an odd looking mix of blue and black blobs in the back ground. However, both of those really are minor and I would only collect more data is you wanted to eliminate the visible noise altogether.

In my opinion a nice looking rendition of this globular.

[Octane]

I agree with Paul, re: more data for less noise.

Also, the coloured blobs are large scale noise, which seemed to be taken care of by MMT.

H

[PRejto]

Hi Paul, (and H.)

I cannot disagree with you about the benefit of longer imaging time. However, in this case I was borrowing the TAK TOA-67 from a generous friend and I now have ordered my own. So, I'm out of luck for getting more data for the time being. Processing will be the end game now.

Peter