Ron Roper's Jupiter sharpening using RegiStax
I know I've been posting a lot of planet photos of late. But we're getting late into planet season now, so I have to strike while the iron is hot.
This isn't quite a planet imaging story, though. It's about image sharpening and how effective it can be. Sure, it's related, but it can be applied to any image - not necessarily planetary, and not even astronomical.
Ron Roper has an Evolution 800 EdgeHD. He also uses a 2.5x Barlow with a ZWO ASI290MC planetary camera. He took an image of Jupiter, (a processed stack of the best 25% of about 6000 frames).
As you can see, Ron's initial image is very impressive. You can see the Great Red Spot (GRS), and maybe just make out Io out to the left which is casting a shadow on the planet.
But that was just the start. Ron was able to sharpen his image up.
He opened it in RegiStax 6 - a free image processing package - and got to work.
RegiStax uses something called wavelet sharpening. Wikipedia has an explanation of the maths... that made no sense to me whatsoever. Suffice to say, it's intended to take a blurry image and find details in the chaos.
As far as I can gather, the idea is to detect edges in the blur. Once it has identified the edge, the algorithm enhances the contrast by brightening the bright side and darkening the dark side.
RegiStax has six layers of wavelets, each of which has adjustable amounts of sharpening, de-noising and overall application. There isn't an agreed conventional strategy on how to choose settings, but through experience, Ron has developed a "usual wavelet sharpening" regime.
And as you can see, the result is utter magic. Ron has been able to delve into the blur, find details and bring them out. Lanes of clouds are better defined, cloud details are visible, and the GRS is well defined. But most striking, Io and its shadow are clear and sharp against their backgrounds.
I've just been sitting here staring at it! Amazing work, Ron.