There was some nice weather on Earth and some exciting activity in the Sun’s chromosphere so I decided to tests some new things in terms of DAQ and image processing. I captured with FireCapture 8bit SERs, realised too late that Halpha is better with higher bit depth. For processing, I stacked the 10% best frames as usual with AS! and I tried ImPPG for sharpening for the first time. I’ve found it very powerful, but I am still unsure about how to really get the output I want. The tone curve looks like being very powerful but I am not sure how to use it. How would you process it ? Your feedbacks are very welcome !

This is the original stacked image (png here):

2026-04-18-0919_4-u-g-sun_halpha_AS_P10_lapl3_ap201.png

Sharpening and leaving the tone curve as is, just a little stretch:

2026-04-18-0919_4-u-g-sun_halpha_AS_P10_lapl3_ap201_imppg_sunspot03.png Tone curve:My feeling: nice, I like it, similar to what I usually obtain with Registax but probably a little more subtle, nicer details.

I explored tuning the tone curve to give a little more crisp and make the fibrils come out. Same sharpening with heavily tuned tone curve:

2026-04-18-0919_4-u-g-sun_halpha_AS_P10_lapl3_ap201_imppg_sunspot04.png Tuned tone curve:My feeling: there is a nice 3D effect, but we loose a bit of the details in the fibrils and in the sunspots.

Inverting the tone curve can bring details up. But my problem is either that the sunspot becomes white which is not so natural, or that an arbitrary level becomes the bright level, like the edge of the sunspot here, again not so natural:

2026-04-18-0919_4-u-g-sun_halpha_AS_P10_lapl3_ap201_imppg_sunspot02.png Inverted tone curve:

My feeling: best renders the details, but the sunspots’ boarder is denaturalised with this bright effect. I could leave the sunspot white, but again, not so natural.

What are you thoughts? Any recommendation for the process?