Trifid Nebula

[sjastro]

Experimenting with PixInsight and an STXL-11002.

Generally common objects don't interest me unless trying out new hardware or software.
I might try colour as part of the experimenting in PixInsight.
Anyway monochrome has a certain charm about it.

2 hrs exposure BRC-250 scope.

Larger resolution here.
http://members.iinet.net.au/~sjastro/Trifidl.jpg

Clear skies

Steven

[jase (Jason)]

Excellent Steven. You've got the BRC really singing for you now. This is the sort of resolution I would be expecting for such an instrument. No doubt the sampling with the STXL has greatly influenced the result. If the luminance is anything to go by, I can't wait to see the end result with colour data added. Your 'natural looking' methodology to processing should make this a stand out, though M20 does look good with a lollipop level of saturation. Your set up has framed it very well, with 'space' around the main feature. Hope the skies clear soon so you can complete the mission. Well done.

[dvj (John)]

I cannot resist commenting on an image with really sharp stars like this one across the entire field. Great dynamic range in the nebula too without that over-processed look.

j

[telecasterguru (Frank)]

Very tight indeed.

[sjastro]

Originally Posted by telecasterguru

Very tight indeed.

Thank you Frank.

Originally Posted by dvj

I cannot resist commenting on an image with really sharp stars like this one across the entire field. Great dynamic range in the nebula too without that over-processed look.

j

John
The frustration is that the sharp stars across entire field is not reproducible.
The STXL11002 is a heavy CCD and flexure is unpredictable.

Originally Posted by jase

Excellent Steven. You've got the BRC really singing for you now. This is the sort of resolution I would be expecting for such an instrument. No doubt the sampling with the STXL has greatly influenced the result. If the luminance is anything to go by, I can't wait to see the end result with colour data added. Your 'natural looking' methodology to processing should make this a stand out, though M20 does look good with a lollipop level of saturation. Your set up has framed it very well, with 'space' around the main feature. Hope the skies clear soon so you can complete the mission. Well done.

Thanks for your ever concise comments Jase.

Clear skies

Steven

[multiweb (Marc)]

That's one gorgeous field Steven. Sharp as with a lot of details. Great lum. You can even see the jet inside the core.

[sjastro]

Thanks Marc for your comment.

The cool thing about PI is the pixel maths has a sufficient number of functions to allow to allow some sophisticated processing.

I've developed a stetching routine that allows fainter detail to be brought out without increasing noise and more importantly not burning out brighter detail or increasing star sizes by an appreciable amount.
Basically the maths behind the stretching is a damped sinusoidal function which leaves the higher pixel values untouched. The function has also been phase shifted not to increase noise or effect very low pixel values.

The new routine is here.
http://members.iinet.net.au/~sjastro/Trifidl_clone.jpg

The original here.
http://members.iinet.net.au/~sjastro/Trifidl.jpg

The routine is still a work in process.

Regards

Steven

[multiweb (Marc)]

Very cool. Is that a scripted add-on you did. You'll have to post your code when it's finalised. Sounds great.

[sjastro]

Originally Posted by multiweb

Very cool. Is that a scripted add-on you did. You'll have to post your code when it's finalised. Sounds great.

It's not scripted at this stage.

The pixels in a previously stretched image are remapped according to the formula.
exp(-0.15*Image)*sin(pi/3*Image)

The graph of the function is attached.
It shows a large percentage of pixels in the shadow and midtone range are remapped by this function. The highlights are largely unaffected.

At this stage I've tried this mapping on a number of luminance images without any disastrous results.

Regards

Steven

[multiweb (Marc)]

Originally Posted by sjastro

It's not scripted at this stage.

The pixels in a previously stretched image are remapped according to the formula.
exp(-0.15*Image)*sin(pi/3*Image)

The graph of the function is attached.
It shows a large percentage of pixels in the shadow and midtone range are remapped by this function. The highlights are largely unaffected.

At this stage I've tried this mapping on a number of luminance images without any disastrous results.

Regards

Steven

Thanks for the info - will certainly try this.

[sjastro]

Tell me how you find it.

It works on colour images as well.
Incidentally you need the rescale result box checked.

Regards

Steven

[RickS (Rick)]

Hi Steven,

Thanks for that. Just giving it a try on some data from the weekend. Looks like a useful tool to have in the processing arsenal!

Cheers,
Rick.