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Sun in Ha: 5/21/2024

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#1 gstrumol

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Posted 21 May 2024 - 10:44 AM

Took the PST out early this morning. Seeing was listed as below average in Astrospheric, and verified visually! wink.gif It was a fairly dull Ha sun this morning, compared to recent days; few and muted filaments, and only one prominent prom.

 

Here are the results:

 

at1.jpg

(click to enlarge)

 

first taken with the zoom EP set to capture the full disk. Then setting it to maximum zoom (8mm):

 

at2.jpg

(click to enlarge)

 

Finally, here is a comparison of two different tone curve shapes, applied to the zoomed image:

 

at3.jpg

(click to enlarge)

 

A sinusoidal tone curve produces an inverted image that easily includes the prominences. Once inverted in GIMP you get dark prominences and a darkening around the rim, giving a hemispherical look to the disk. The more monotonically increasing curve (right) tends to remove the prominences but gives a more uniform disk appearance.


Edited by gstrumol, 21 May 2024 - 02:25 PM.

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#2 David Rosenthal

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Posted 21 May 2024 - 12:18 PM

Nice images Gary and thanks for the IMPPG curve samples, I struggle with that tool


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#3 David Rosenthal

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Posted 21 May 2024 - 12:38 PM

Gary,

I took my last image into IMPPG, started with your curve, and tried this to keep the background dark and the proms visible. Kind of a cool effect.

Attached Thumbnails

  • Screenshot 2024-05-21 at 1.34.40 PM.png

Edited by David Rosenthal, 21 May 2024 - 12:42 PM.

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#4 gstrumol

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Posted 21 May 2024 - 12:44 PM

Gary,

 

I took my last image into IMPPG, started with your curve, and tried this to kappa the background dark and the proms visible.  Kind of a cool effect.

Yes, that is the third type of tone curve I sometimes use. I call that one 'the hump' because of the initial bump in the curve before coming down and proceeding 'normally'. waytogo.gif

 

hump.jpg


Edited by gstrumol, 21 May 2024 - 12:46 PM.

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#5 rigel123

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Posted 21 May 2024 - 09:23 PM

Took the PST out early this morning. Seeing was listed as below average in Astrospheric, and verified visually! wink.gif It was a fairly dull Ha sun this morning, compared to recent days; few and muted filaments, and only one prominent prom.

 

Here are the results:

 

attachicon.gif at1.jpg

(click to enlarge)

 

first taken with the zoom EP set to capture the full disk. Then setting it to maximum zoom (8mm):

 

attachicon.gif at2.jpg

(click to enlarge)

 

Finally, here is a comparison of two different tone curve shapes, applied to the zoomed image:

 

attachicon.gif at3.jpg

(click to enlarge)

 

A sinusoidal tone curve produces an inverted image that easily includes the prominences. Once inverted in GIMP you get dark prominences and a darkening around the rim, giving a hemispherical look to the disk. The more monotonically increasing curve (right) tends to remove the prominences but gives a more uniform disk appearance.

Does Gimp allow you to raise shadows?  I think if it can do that you can bring the proms out on that image on the right.


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#6 gstrumol

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Posted 21 May 2024 - 09:51 PM

Does Gimp allow you to raise shadows?  I think if it can do that you can bring the proms out on that image on the right.

It can be done with a modification of the hump:

 

toney.jpg

(click to enlarge)

 

but it's a delicate balance of prominence and surface detail. And the prominences aren't as 'prominent' as in the other approach.


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