Tone down Red Tint

[jerryyyyy]

Shot some images LRGB of M83 which is very close to the horizon for me and it comes out pretty Red.  Have tried ColorCalibration and Assisted ColorCalibration... I think that later might do it, but it does not seem to apply the changes properly.  Any suggestions?  This Red is quite substantial and a bit beyond the norm. 

[GJL]

Perhaps SCNR, Coloue Red, try different values.

Gerhard

[jerryyyyy]

You know what finally fixed this.  On the initial stretch using STF, I checked the Link RGB Channels button....

[Harry page]

Hi

If you watch this vid http://harrysastroshed.com/RGB%20Combination.html

There is a bit on linear fit which should sort you out

Harry

[pfile]

You know what finally fixed this.  On the initial stretch using STF, I checked the Link RGB Channels button....

after color calibration, it's pretty important to re-link the channels and recompute the STF. otherwise it's possible STF will undo all the hard work you did… and then if you transfer it to HT, you destroyed the color balance.

rob
 

[jerryyyyy]

Thanks everyone.  I looked at the video and seems like child's play 

However, there is some ambiguity in the video.  I think the steps are:

1.  Get the stacked RGB images.
2.  DBE the images... if I ChannelCombine these looks RED
3.  LinearFit to the least noisy one... green in my case.
4.  ChannelCombination
5.  STF linked
6.  HTF

End result dioes look better, especially after SCNR to get out green....

Is this the path? 

[pfile]

somewhere in there you should be doing BackgroundNeutralization immediately followed by ColorCalibration…

rob

[jerryyyyy]

somewhere in there you should be doing BackgroundNeutralization immediately followed by ColorCalibration…

rob

Thanks, I have put up some new versions of M86 M87 on Astrobin with this advice.  Looks better. 

[pfile]

yeah - that looks a lot better

rob

[jerryyyyy]

PI is very powerful but there are so many details like this that learning curve keeps expanding...

[GaryP]

somewhere in there you should be doing BackgroundNeutralization immediately followed by ColorCalibration…

rob

I have a vague memory of one of Harry's tutorials that BackgroundNeutralization is not necessary after DBE. Wrong?

[pfile]

DBE, when "normalize" is not ticked (the default) tends to neutralize the background, this is true.

but i always do BN anyway for good measure 

[Harry page]

somewhere in there you should be doing BackgroundNeutralization immediately followed by ColorCalibration…

rob

I have a vague memory of one of Harry's tutorials that BackgroundNeutralization is not necessary after DBE. Wrong?

Hi
I think I say something like after DBE  a neutral background should be a by-product and therefore using BN would not change anything , but if you are not sure

No harm in using it

Regards

Harry

[GaryP]

What exactly does "neutral background" mean? Does it mean the colors in the background are balanced?

[Harry page]

Hi

Yes a neutral background is equal in weight for RGB , something you should keep a eye on during processing, You can use BN at any time during processing

Harry