Getting colour from the moon?

[Stub Mandrel]

This is yesterday's APOD:

When I saw it, I suddenly realised that the 'colour artefacts' I saw on my own moon picture weren't artefacts at all. Less pronounced, but only visible at 50% zoom, they mimic the distribution of colours (brown/cyan) in the above picture.

But for some reason I can only see them at 50% zoom, the picture goes grey when zoomed in or out! resampling teh picture makes it grey too, but a screen grab shows the effect:

(Sadly no ISS included)

Clearly it's something to do with debayering of the CRW files and what PIPP does to the image. But obviously using a screen garb and 50% resolution is losing a lot of precious data! How should I debayer in PIPP to be able to process these colours properly?

[Bizibilder]

All you need is an RGB (ie colour) image and some software that will boost the colour saturation.  Photoshop or GIMP will do it.

This is one from 2011 - the processing is a bit rough but it shows what you can do with a DSLR and full frame shot:

[Stub Mandrel]

I've got the colour images, but if I process them in PIPP they seem to lose the colour - except when zoomed 50%. This must mean I'm debayering them wrong in PIPP?

[Bizibilder]

There is a tick box in PIPP - under processing options to "convert colour to monochrome"  maybe you have that ticked?

[Stub Mandrel]

No, they aren't converting to mono. If I pump up the saturation the moon turns orange! The same happens to RAW images converted to TIFF by Raw Therapee.

But if I take the stacked image, zoom to 50%, I get the effect above  which is clearly NOT an artefact as the colours are in the same places as the APOD pic :-/

[Moonshane]

Weirdly this is how i see the moon with my old ethos and my current delos and 26mm Nagler but not my older nagler. Maybe my eyes and the coatings are better than I realised!

[JamesF]

I'm not sure I see how it can be PIPP.  The colour information must still be there even if you can only see it at one image size.  There are lots of different debayering algorithms, but they don't tend to affect the colours that much (though they will do fractionally as they give surrounding pixels slightly different weights when calculating the final colour of any specific pixel).  They tend to be more targeted towards getting better representations of hard edges and reduction of artefacts due to the fact that the image is made of square pixels.

The fact that you can see it at some resolutions and not others could perhaps be an artefact of the rescaling process?  Maybe at full size your eye isn't sufficiently sensitive to perceive it whereas at 50% there's sufficient density of colour to pick it up and then as you go smaller still too much information is being thrown away and you lose it again?

There are some tutorials about processing the Moon to give colour somewhere online.  It could be worth trying that with the full size image to see if it's possible to pull any colour out?

James

[Stub Mandrel]

It's really, really odd. I have tried working on a single frame, and I can't get any colour other than orange out of it! I give up :-(

[JamesF]

Is it worth trying on a single frame without any other processing?  It may not be the debayering, but it might be some other part of the process.  Going through everything one step at a time might reveal the cause.

James

[Stub Mandrel]

That's what I did, opened it in Raw Therapee, saved as 16 bit tiff and straight to the saturation controls in photo paint.

[JamesF]

In that case I think I'm out of ideas

James