Iris Nebula and a hello

[rjbokleman]

Sean, Thanks for the processing details! I'll try to take some notes when I'm processing my next image and include them when I post it.

Can you explain the benefit of the LinearFit L to Lum part? That will match the RGB luminance to Lum, right?

Andy,

Jon Rista has an interesting take on LinearFit here: https://jonrista.com/the-astrophotograp ... linearfit/

I use it earlier in my post processing than Sean did in this example, but Jon does make mention that LF can be beneficial later on as well.

[AndyG]

Thanks Ron. What I was actually trying to ask about was Sean's thoughts on applying LF in the way he did at that point in his process.

[dodgeandburn]

Andy,

The reason I do the LinearFit is due to finding this post that described the method. I liked it because it seemed to remove most of the guess work out of stretching the L and RGB "by eye" before combining, and makes it seem more repeatable (I like repeatable). This Iris Nebula image is actually my first LRGB image. Before this I've done only RGB because I couldn't get LRGB to work well enough. But this object seemed to really need L, so I dug in and tried to figure it out. It helped a lot.

Ron,

The Jon Rista page is interesting in terms of using LinearFit for a basic initial color calibration. Thanks for that link. I'm going to try that the next time as I do feel like my color is just slightly off sometimes and I struggle with it.


Chuck,

I think PixInsight could compliment Nebulosity because isn't Nebulosity just for acquiring frames? Pixinsight will work with DSLR, that's what I used to use, and it just means you have to take 1 or 2 extra initial steps to convert & de-bayer the images. In any case, I'd be happy to help were I can, but I'm still learning lots!


TomH,

Thanks! LP is a pain... would like to have a dedicated observatory in NM... or even on the Cape would be fine, too.

[AndyG]

Andy,
The reason I do the LinearFit is due to finding this post that described the method. I liked it because it seemed to remove most of the guess work out of stretching the L and RGB "by eye" before combining, and makes it seem more repeatable (I like repeatable).

Ah yes, I see now. I just applied the technique on an image I am working on and you're absolutely right, it removes the guess-work in matching the Lum and RGB stretches. Thanks for the tip!

[Chuck]

Chuck,

I think PixInsight could compliment Nebulosity because isn't Nebulosity just for acquiring frames? Pixinsight will work with DSLR, that's what I used to use, and it just means you have to take 1 or 2 extra initial steps to convert & de-bayer the images. In any case, I'd be happy to help were I can, but I'm still learning lots!

Sean,

Yeah, Nebulosity can be used for acquiring images but I use Backyard EOS, as that's what I started with. Nebulosity is also used for processing images but it's not as powerful as PixInsight. The draw of Nebulosity is its simplicity for those starting out like myself. If or when I decide to take the PixInsight plunge, I'd welcome your help, thanks.

---- Chuck

[AndyG]

10. HistogramTransformation - close in on final stretch, but not too far.
11. Enable mask to protect stars from blooming too much.
12. Final HistogramTransformation stretch.

Sean, I used this part of part of your processing strategy to reduce the bloat in large stars and it worked quite well (thanks!). More recently, I came across a similar technique that uses MaskedStretch for similar effect which I now like even better. Harry's Astro Shed has a very good tutorial video (the Masked Stretch button at the bottom).