Comparison of sharpening methods for Moon images

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DavidWright2010 Senior Member • Posts: 2,659
Comparison of sharpening methods for Moon images

The wavelet sharpening in RegiStax 6 (nfi) is pretty much the standard technique for sharpening lunar images. But Topaz Sharpen AI (also, nfi) can do pretty impressive things, and has very few user-controls to confuse folks. (I admit I am not an expert in the use of the wavelet technique even tho I've read the tutorials on the subject.)

But we know the 'ground truth' of what we should see in a lunar photo. Here I compare an image from the Lunar Reconnaisse Orbiter (LRO) in the center, with wavelet sharpening (LHS) and Topaz (RHS) I did a little further adjustment in both of my photos.

This region of the Moon shows Hadley Rille (slightly right and down from center), which is that sinuous feature in a small valley and has a small crater touching it. This area was visited by the Apollo 15 astronauts.

The LHS and RHS images are shown at abou 600%, to match the scale of the LRO image. The match is not exact because the LRO image was (probably) taken from directly overhead, while we see this region at an angle.

Topaz makes what seems to be a sharper image, but it does so by 'eroding' features. Look at that chevron-shaped feture at the top, slightly left. Topaz (RHS) thins it out and it looks nothing like the real thing. Wavelets do much better.

Likewise, the small crater that touches the Rille is practically invisible after Topaz did it's thing, but is clearly visible after RegiStax wavelet processing.

You may be aware that Topaz has three modes of sharpening - focus, stabilize, and sharpen. The one that I showed in the comparsion above was focus, because I thought that did the best in this situation. Here are all three - focus stabilize and sharpen.

Stabilize is inventing diagonal features here (they all do, to some extent). Sharpen is different than focus, but IMO not any better.

So my opinion, wavelet processing may seem not as sharp as Topaz, but it gives a more accurate result.


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