705 replies to this topic

[the Elf]

Dears,

 

many of us don't know what to do during the pandemic lockdown and many cloudy nights. So I put a bunch of stacks on my homepage free to download and play with. There are projects from simple to a bit tricky.

Here is the link:

 

http://www.elf-of-lo.../Downloads.html

 

Enjoy!

Feel free to post your results here.

 

all the best

the Elf

[the Elf]

Technical question: is there any benefit in fits over 32bit tif? As my webspace is limited and I want Gimp and PS users to have access I uploaded everything as a 32f tif.

[fewayne]

Good one!

 

I am currently exceedingly busy pressing the "refresh" button on the order for my CEM70 while staring hopefully at the screen, so probably won't get to it :-) .

 

But I applaud your continued efforts to help us all along. I'm sure there are other online communities whose members work so hard to support one another but astronomy is the best one I've encountered so far. Thank you.

[klaussius]

Technical question: is there any benefit in fits over 32bit tif? As my webspace is limited and I want Gimp and PS users to have access I uploaded everything as a 32f tif.

Not really for stacks.

 

FITS have the headers which include data about the equipment used and the object. It may help with color calibration, but if you include that metadata separately it doesn't really matter much.

[KenwardV]

Thank you, Elf!  I am playing with PI now, and likely others later on.  My equipment won't be here for 10 weeks or so, so I thought I'd work on learning this side of things in the meantime.

 

Kenward

[F.Meiresonne]

Here is one

 

Nice , very clean stack.

 

Allthough could use some more integration time imho

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[jonnybravo0311]

Took a stab at M33:

 

 

Tried to not be too heavy-handed on the edits. Processed using PI.

[Spammy]

Thanks for sharing, always good to be able to practice processing. (Our last clear night here was December 9) 

[Stelios]

Technical question: is there any benefit in fits over 32bit tif? As my webspace is limited and I want Gimp and PS users to have access I uploaded everything as a 32f tif.

Depending on capturing program, .fits may contain enough info for PCC to just grab data from image. 

[robonrome]

thanks Elf. A great exercise and much appreciated. I still havent got to grips with PI and maybe never shall. I've been using Startools and finishing in PS. Here's a quick and dirty 30min via startools/PS on the Rosette OSC colour data only. If i get some more time may explore some of the other options.

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[F.Meiresonne]

Mmm,

 

This one was more difficult then i thought it would be.

Nice clean stack, quite some detail.

 

Allthough the colors could be better. Tried also to reveal the dust around the nebulea

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[the Elf]

 

This one was more difficult then i thought it would be.

You solved the puzzle quite well! The great contrast between the trap area and the dim clouds is a challenge. Local histogram equalization helps a lot. You might try HDR methods as well. I haven't tried.

[F.Meiresonne]

Thanks

 

 

Now this one was a pleasure to work on...

Again a nice clean stack, great detail  , a real nice shot....

It did not take much time to get a result

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[imtl]

Freddy,

 

You should run some SCNR on green on the last image you processed.

[F.Meiresonne]

Green?

 

Does it look green? Can you explain a bit more..

[imtl]

Your stars have a green cast and also there is some green on the galaxy. Maybe it's the jpg or my stupid screen. But that's how it looks.

[F.Meiresonne]

I did not see it.

However on my laptop here it is not that what i get on screen i use to process...

I use a Benq QHD , image is Always better there,

 

However i notice now some in the galaxie now you mention it,however not on the stars, but they are not so colorfull as on the Benq..

 

I am starting to believe that my eyes are not very sensitive to green, because you are not the first one that makes a remark on that...

Edited by F.Meiresonne, 09 January 2021 - 06:16 AM.

[F.Meiresonne]

Well FWIW another attempt.

 

Maybe a bit less greenish although i don't see much.

 

Overall i find this image not particulary better then the one before...

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[imtl]

The previous one is much better. You've got some clear processing artifacts in the last one you posted.

 

With the previous one try the following:

1. Invert your image.

2. run correctmagentastars script in PI, try to use 0.4 to start with.

3. Invert back.

 

Of course there are plenty of other ways to do this and also the use of masks will give much more precise results but its a simple fast way to do it.

[the Elf]

Freddy,

 

when you start, you probably have an idea if you want a very colorful eye candy image or if you want just a slight pastel touch. Usually I am not so much on the colorful side until I have finished the image and compare it to other versions on astrobin. That is when I go back to an early stage and try add more color. That is why this time the original is very color full. I'm posting it here not to say it must be so saturated but to discuss the colors you find in a galaxy in general. So here is my image

 

 

Galaxies evolve over time. Young stars get born in the spiral arms, the older ones gather in the center. Stars that burn blue don't live long. Stars that burn yellow or red save fuel and live much longer. That is why many galaxies are golden in the center. If there are blue stars they are in the spiral arms. That is why the spiral arms are blue. Galaxies are dirty. There is dust that fades the light to brown. That is what we see in the milky way and here as well. So basically you should end up with a golden center, blue arms and brown dust. There are Ha clouds glowing in red in the radiation of the young blue stars. This is missing in my data because it is not modded. I'd like to shoot Ha but the clouds don't let me. Anyway, golden, blue, pink, brown. What is missing? There is absolutely no green in space other than O-III which is teal but not green. Any green in an image is noise in the green channel and can be removed completely.

All the stars in the image are foreground stars in our own galaxy. They have all sorts of color that a Planck radiator can have, like a light bulb from yellow to white and blue. Again, no green.

So during procession you want to balance color in a way that all the colors are there and all the green is removed. If you finally make a neon image like mine or a more gentle touch of color is your decision but one would expect to see some sort of color variation as described above. Problem is, stretching removes color. So you either have to add saturation or you have to stretch in L*a*b* and steepen the a* and b* component. Bracken explains it in his book. In PI there is Mark Shelly's (CN: sharkmelly) arcsinh stretch that preservers color while stretching. There is some sort of stand alone version of it, I don't know the details. You will find it. No matter which tool you use, the task is to preserve the color and to keep the noise out. Not an easy task.

[Der_Pit]

Technical question: is there any benefit in fits over 32bit tif? As my webspace is limited and I want Gimp and PS users to have access I uploaded everything as a 32f tif.

Except for the additional info in the FITS header it's the same.  However, some of my applications had issues with the used 'deflate' compression type (older ones, admitted).  GIMP does read FITS btw. 

[F.Meiresonne]

The previous one is much better. You've got some clear processing artifacts in the last one you posted.

 

With the previous one try the following:

1. Invert your image.

2. run correctmagentastars script in PI, try to use 0.4 to start with.

3. Invert back.

 

Of course there are plenty of other ways to do this and also the use of masks will give much more precise results but its a simple fast way to do it.

Trouble is i don't use PI. That is still way over my head...

[Borodog]

Except for the additional info in the FITS header it's the same.  However, some of my applications had issues with the used 'deflate' compression type (older ones, admitted).  GIMP does read FITS btw. 

I have found you have to uncheck exporting a color profile in GIMP when exporting to a different format, otherwise the resulting file looks different when you open it in different software. 

[imtl]

Elf,

 

I took a look at your M27 data. I did some quick HOO with RGB stars. No decov (not enough SNR for that IMO). Just played with localhistequalization and a bit of colors. Your OIII data is near clipping the blacks as far as I can see. You should consider recalibrate with a pedestal. I didn't go in depth to try and squeeze the outer faint glow of the nebula since the I don't like a lot of NR (which I did a bit in linear stage) and the SNR does not allow to push the data so much. Also, I'm lazy

 

Anyways, I kept things subtle and fast, I kind of like a brighter background but the OIII data prevented that. Probably I can invest more time into this or maybe someone with actual skills can push it more but meh... This is just for fun. I'm bored with re-processing my own data. You got some halos around stars in your OIII data

 

[F.Meiresonne]

Great detail.

 

But i miss a bit the stars in the nebulae itself.

 

But  again the nebuale stands out terrific...

 

Guess i will have to download some more stacks. More processing excercise...

 

I am grounded. Can't leave the house, got a fever(went away), fatigue and coughing...

So test next Friday on Covid.

I don't think i have it, because i did not loose my taste nor apetite....

But one never knows for sure...