Akastroid vs RegiStax

They do different jobs

RegiStax is used today mostly for one stage: wavelet sharpening of an already-stacked planet, usually stacked in AutoStakkert. Akastroid does the whole chain (grading, stacking, dispersion correction and sharpening) for planets and for deep sky, in one application on Mac, Windows and Linux.

So the comparison here is narrow: six sliders you set, against a sharpening strength measured from the stack.

Sliders, or a measurement

RegiStax gives you six wavelet layers and lets you take any of them as far as you like. In experienced hands that gives more control than any automatic setting. It also has no idea what your stack can support, so overdone wavelets (bright rims around every belt, a ringing limb) are the most common way a good planetary capture gets spoiled.

Akastroid measures instead: how much fine detail the stack holds, how much noise sharpening would amplify, and whether the limb starts to ring. The strengths follow from that, and if a stack cannot take sharpening, it is left alone.

The measurement

One capture. The same Mars stack was sharpened twice: in RegiStax 6 by a RegiStax user with his own wavelet settings, and in Akastroid at its default Sharpness, both saved at the camera's own 352 pixels so neither is flattered by a finer grid.

• Fine detail, 1-2 pixels: 0.0111 against 0.0111. Level. Earlier that day ours held 70% of RegiStax's at that scale and 45% at 1 pixel; the gap closed when the default was re-measured at camera size rather than on the working grid.
• The limb: no ringing on ours. Overdone wavelets show first as a bright rim and a dark gap at the edge of the planet. Akastroid measures the limb's profile and declines the sharpening that would ring it; the same ruler gates every release.
• Brightness: 0.545 against 0.566 at the disc's median. That is the same exposure to within 4%, which matters because a brighter picture looks sharper.

What this does not say: that Akastroid is sharper. Equal numbers read as equal, one capture is not a survey, and the RegiStax side depends on where one person put six sliders that afternoon. A Saturn comparison goes here when a RegiStax result of it exists, whichever way it falls.

Use both, if you like

Akastroid's stacked export is linear 32-bit data, written so another program can pick it up. Stack here and sharpen in RegiStax, or the other way round. Neither tool requires you to use it for the whole workflow.

Questions

Is Akastroid sharper than RegiStax?

Level, on the one capture measured, with a cleaner limb. The same Mars stack was sharpened in RegiStax 6 by a RegiStax user with his own wavelet settings and in Akastroid at its default, both saved at the camera's own 352 px. Fine detail at 1-2 pixels measured 0.0111 on both. Where they differ is the edge of the planet: Akastroid's limb shows no ringing or bright rim by the same ruler its regression tests use, which is the fault overdone wavelets produce first. One capture and one person's sliders is not a survey, so the claim stops at level. A Saturn comparison goes here when a RegiStax result exists to measure against.

Does RegiStax still work?

Yes. RegiStax 6 is from 2011 and Windows-only, and its wavelet sharpening is still very good. That is why people still recommend it fifteen years on.

What does Akastroid do instead of wavelet sliders?

The same idea, with the strength set by measurement. The stack is split into scales and each is sharpened as far as the stack can support, judged by how much real detail it holds and how much noise sharpening would amplify. The Sharpness control moves all of it together in four steps, and the detailed rows are there when you disagree. You cannot spend an evening on six sliders. Some people will miss that.

Can I use both?

Yes, and some people should. Export the stack as a 32-bit float TIFF or a FITS master and sharpen it wherever you like. Akastroid's stacked export is linear data written for that. Nothing about using Akastroid to stack commits you to its finishing.

Does RegiStax run on a Mac?

Not natively. It needs Wine, CrossOver or a virtual machine, and Wine on recent macOS has been awkward. For Mac planetary imagers that is usually the reason to look elsewhere, more than any feature.

The planetary path is described on the planetary page, and how wavelets and dispersion correction work is the guide behind it. Download for Mac and sharpen a capture you have already done in RegiStax, then compare the two.