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  #21  
Old 07-06-2019, 08:47 PM
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fine image indeed Lee congrats
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  #22  
Old 08-06-2019, 07:45 PM
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codemonkey (Lee)
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Thanks very much Peter, Marc, Suavi and beren :-)

What's everyone's thoughts on the colour? It's interesting to compare this one with Mike and Peter's recent efforts. I'd like to point out that the point of this post is not to cause argument about which of these images is better, it's just interesting to compare the different approaches/results.

Mike's one is reasonably neutral in colour, Peter's looks a bit more blue. Mine clearly has a lot more red than either of those.

Truth be told, I prefer the more neutral / blue colour in terms of aesthetics and I've produced images in the past that have been more like that.

The image in my original post used PhotometricColorCalibration in PixInsight with default white reference. From there, I did drop the red a touch, but as you can see in my image, it's still a lot more red than is often shown.

Note that Vincent Peres and Juan Conejero claim the default white reference used in PCC is the "best unbiased white reference, truly representative of the observed deep sky"

I did some cursory reading... typically I'm just a "pretty picture" astrophotographer, I have little to no understanding of the science, so I could be wrong here and I'd appreciate correction if I am.

My understanding is that the exact classification of Cen A is subject to debate, but it's considered to be either an elliptical, or a lenticular galaxy. My understanding is that both of those galaxy types tend to be populated mostly by older, red stars.

I found this abstract which seems to confirm that: "bulk of the stars with ages in excess of ~10 Gyr"

So based on this, I'm of the understanding that Cen A is probably a bit more red than is often shown... but frankly I don't think it looks as nice that way ;-)

Attached is a quick process using a non-standard white reference, specifically that of an elliptical galaxy. It has a lot more blue and looks closer to Mike and Peter's images in terms of colour... I personally think it looks better than my initial version. Maybe this could be considered more correct in colour from the perspective of a viewer within Cen A?

Something else to consider: how much do we actually care about the truth of the colour, whatever that is?
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  #23  
Old 09-06-2019, 09:05 AM
RobC (Rob)
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Lee you have raised a very interesting point. I am compelled to use PCC for colour balancing because I am red green colour blind. Last year I posted a very detailed image of M83 but got criticised by an IIS turkey because my image was lacking saturation in the blue wavelength. As a result of this criticism I have been hesitant to post images.

Glad to see you pointed out that PCC is considered to produce technically correct colour balanced images.

Cheers

Rob
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  #24  
Old 09-06-2019, 11:30 AM
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Nice shot Lee, love the colour and the detail is nice too.
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  #25  
Old 11-06-2019, 07:10 PM
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codemonkey (Lee)
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Quote:
Originally Posted by RobC View Post
Lee you have raised a very interesting point. I am compelled to use PCC for colour balancing because I am red green colour blind. Last year I posted a very detailed image of M83 but got criticised by an IIS turkey because my image was lacking saturation in the blue wavelength. As a result of this criticism I have been hesitant to post images.

Glad to see you pointed out that PCC is considered to produce technically correct colour balanced images.

Cheers

Rob
I wouldn't let a single comment prevent you from submitting images, Rob. It is interesting how different the supposedly correct rendition is from what we typically see though... it's certainly not the norm.


Quote:
Originally Posted by Paul Haese View Post
Nice shot Lee, love the colour and the detail is nice too.
Thanks Paul :-)
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