M63 Photometric Colour Calibration or Classic Colour Calibration?

[wimvb]

PixInsight has two methods for colour calibration: the "classic" process, where you choose a background and an area that is to be used as a white reference, and the photometric process that tries to use photometric star information to create "natural" colours. The two processes can give very different results. I always found that my previously posted version of the Sunflower galaxy (M63) looked a bit red, so I reprocessed it, but used classic colour calibration followed by scnr, because the galaxy had a slightly green tint.

Here are the results; first the original, PCC version and next the new CC version.

Which one do you prefer?

PCC:

CC:

Btw, reprocessing the image took only about 5 minutes. I just applied the process container of the PCC version to the CC image. A two click process. I just love PixInsight!

And for those who can't make up their mind, here's also an average of the two:

[glowingturnip]

well to me, I'd say the stars in the classic version all seem to be a pale shade of purple ?  I'm a sucker for sciencey things so would always go for the PCC but it does make your galaxy look a little red.

Did you apply Background Neutralisation after PCC by the way ?

[wimvb]

The stars need their own process, so in a proper process, I wouldn't do it this fast way. I could always replace the stars f the cc version by those of the pcc version.

I do background neutralization before colour calibration, even though pcc has its own background neutralization process built in.

[Stub Mandrel]

The second one looks nicer but they all seem to have blotchy green and purple backgrounds?

I use gradient exterminator, even on images without a gradient, and its balance background colour always seems to give me good balanced colours.

[Petergoodhew]

Interesting comparison Wim.  I much prefer the classic.  The PCC version is swamped with red and the blue almost disappears.

[wimvb]

58 minutes ago, Stub Mandrel said:

The second one looks nicer but they all seem to have blotchy green and purple backgrounds?

I use gradient exterminator, even on images without a gradient, and its balance background colour always seems to give me good balanced colours.

 

34 minutes ago, Petergoodhew said:

Interesting comparison Wim.  I much prefer the classic.  The PCC version is swamped with red and the blue almost disappears.

I'll do a proper reprocess of the second one then, and pay extra attention to the background.

[Stub Mandrel]

I used Gradient Exterminator on a screen grab. It's a beautiful, detailed image by the way, Wim

[Firas]

Second image is better. But I think a Magenta color mask will kill off the magenta in the stars. 

[wimvb]

7 hours ago, Stub Mandrel said:

I used Gradient Exterminator on a screen grab. It's a beautiful, detailed image by the way, Wim

Thanks Neil. On my screen the galaxy now seems a bit green, despite me using scnr green on it. I will do a proper reprocess anyway.

Just now, Firas said:

Second image is better. But I think a Magenta color mask will kill off the magenta in the stars. 

Or invert and kill the green with (again, even here) scnr green, then invert back. But as I wrote, I will do a proper reprocessing on this one. I did the quick process container drop just to see if Pixinsight could do this, and still use masks. That seems to have worked.

[MartinB]

Cc for me as far as the galaxy goes.

[Guest]

CC version ?

Oh no! Now I have to go back and do some reprocessing to see if I can get better results like these LOL

By the way, I have no idea why - but I've never suffered from magenta stars in my nb images? I use PixInsight - but the stars always turn out fine?

If I knew why I could market it right LOL

David

[Rodd]

I have always found that I get very similar results using the 2 CC methods--I am surprised you got such a variation.  I like the second one better.  That second image is very nice--a very natural palette.

Rodd

[tomato]

A really nice M63,  the CC version just takes it for me.