Hi all !

I’m relatively new to imaging and even newer to solar H-alpha observation and imaging. I don’t have much experience with other solar scope but I can tell the views on sunspots and prominences through my setup are gorgeous! I’m trying now to improve in solar imaging. I was so far using more or less the same acquisition and processing pipelines for solar as for planetary: 8bit acquisitions on ROI for super high FPS, stacking with AS! and sharpening with Registax. I’m now trying to switch to ImPPG which I have understood is very powerful and more adapted than Registax for solar H-alpha.

My images are always close-up views as the sweet spot of my H-alpha filter is small. So close-up view of regions of the disc (sunspots) or of prominences. Starting with Sunspots, would you tone-invert it or not? My issue is: tone inversion helps to bring this 3D effect and brings the fibrils up. But either we end up with white sunspots or with new bright regions close to the sunspots which are not naturally bright. In full-disc images, I feel like these are not so distubring, but for close-up views, I don’t like them.

Please see my example in https://app.astrobin.com/u/astro_yeye?i=g97wpl where you can find the post-stacking tiff files. They are based on an 8bit acquisition although I’ve just understood that 16bit is better for solar imaging (will try it next time).

This is the original stacked image:

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.pngimage.png

Bringing the high intensities down: bring some nice 3D effect

2026-04-18-0919_4-u-g-sun_halpha_AS_P10_lapl3_ap201_imppg_sunspot04.pngimage.png

Inverted: white sunspots

2026-04-18-0919_4-u-g-sun_halpha_AS_P2_lapl3_ap587_imppg_sunspot01.pngimage.png

Inverted by try to keep the sunspots black: bright unnatural ring around the spot

2026-04-18-0919_4-u-g-sun_halpha_AS_P10_lapl3_ap201_imppg_sunspot02.pngimage.png

What are your thoughts and what is your experience with using ImPPG? What are your optimal settings or how to derive them?

I’m focusing on the tone curve, but if you have advice or feedback on anything else, you would be very welcome!

Additional comment/question is: zooming in ImPPG, I’ve noticed vertical and horizontal lines:

Capture d'écran 2026-04-19 215421.pngThey don’t seem to appear in the final image. Is this just a display thing? Do you have already seen that?