Going deep and deeper in the Orion Nebula region

[MLParkinson (Murray)]

Here is a pair of ‘going deep’ images of the Orion Nebula region, one a (Ha alpha, OIII) rendition, the other a (SII, Ha alpha, OIII) rendition. I posted an H alpha-OIII rendition based on the same data about 2 years ago, but since then I have recorded the new SII data, and also learnt new image processing work flows. I like to think that these two images are an improvement on my previous effort; probably they are just different. Many hours of long exposures were required to go this deep and achieve a satisfactory SNR.

https://flic.kr/p/22tHrP4

https://flic.kr/p/JU9zpk

[RickS (Rick)]

They are certainly something, Murray One suggestion: I think they might look a little better if you turned down the noise reduction a little and left them just slightly gritty?

Cheers,
Rick.

[Peter Ward]

Sorry, I think there is something odd about the colour.

Almost as if the the image as been colourised in Photoshop with no correlation between the actual emission-bands in the nebula and the colours you've presented.

[SimmoW (SIMON)]

Spectacular! Yes orion in nb is so hard to process naturally! Youve got a good start, id revisit more to reduce nr and reduce the orange.

[MLParkinson (Murray)]

Originally Posted by RickS

They are certainly something, Murray One suggestion: I think they might look a little better if you turned down the noise reduction a little and left them just slightly gritty?

Cheers,
Rick.

Thanks Rick. You are probably right. I made use of PI masks (you taught me that) to minimize noise reduction on the bright central parts, and maximize noise reduction on the faintest parts. I also applied stronger detail-enhancing transformations to the brightest central nebulosity. My thinking was reminiscent of classical portraiture photography which makes use of a narrow depth of field to blur everything except the main human subject.

Perhaps I might produce a better image if I applied stronger enhancement to the faint nebulosity as well. Grain or noise is not necessarily a defect in terrestrial photography. Perhaps one day producing grainy astro-images will become the fashion.

[MLParkinson (Murray)]

Originally Posted by Peter Ward

Sorry, I think there is something odd about the colour.

Almost as if the the image as been colourised in Photoshop with no correlation between the actual emission-bands in the nebula and the colours you've presented.

Yes, I have used Photoshop to map the colours, especially for the [SII, Ha, OIII] image. This is standard practice when processing Hubble palette images. The dominant colour change I made is mapping the H alpha green channel towards yellow. I have also executed a few other lesser colour tweaks. I could be in error, but I still perceive a correspondence between the raw data and the final colours in my representations.

Does it really matter anyway? This is an art forum, not a scientific forum. If it were a scientific forum, we would not de-linearize the data, nor aim to create the illusion of 'natural' colour. We would simply respect the data and let it speak for itself rather than impose the limitations of human perception. I have a few ideas brewing on how to produce a living, dynamic image which respects the original data.

[MLParkinson (Murray)]

Originally Posted by SimmoW

Spectacular! Yes orion in nb is so hard to process naturally! Youve got a good start, id revisit more to reduce nr and reduce the orange.

Thank you very much Simon. If I understand you correctly, you are confirming Rick's comment: you would like me to strengthen the contrast and detail in the fainter nebulosity, even if that means more noise in the background. I think that I am starting to perceive what you perceive.

[gregbradley]

That's a pretty wild image. It certainly shows the depth of Ha in the area.
Spectacular in that regard.

Greg.

[SimmoW (SIMON)]

Yes Murray, in photoshop i sometimes layer mask differing levels of noise reduction (on each filter image) to avoid any overall smeared look. Well worth doing it individually or you can end up with up to 3 filters of Noise or NR.

As i say its tough so open to different approaches. Every one of my nb images, months later i have to quell the urge to re-re-process them!