Sharpening over-sampled images

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Beatsy
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Sharpening over-sampled images

Post by Beatsy »

For years I was of the opinion that pixel-level sharp was the only way to go. It didn't take long after joining this forum to be convinced otherwise! There is more detail (resolution) to be gleaned from over-sampled images at high mag (and N.A.). It's not *entirely* empty magnification.

However, the resultant fuzzy pictures continue to irk the "old me" a bit and I've tried many times to make them appear sharper. To date, nothing has worked to my satisfaction. Down-sampling does the trick, but restores sharpness and edge-contrast at the expense of (barely) resolved detail. Sharpening over-sampled imagery just causes halos and other artifacts that look nasty IMO. I tried adjusting radius and used many different sharpening protocols, and combos thereof, but never liked the outcome.

This issue mainly applies to microscope images of diatoms, taken using oil immersion to tease out close spaced punctae and other details at (and even beyond) the theoretical limits of resolution.

Am I missing a trick? Is it possible to improve edge-contrast and apparent sharpness of grossly or slightly over-sampled images without down-sampling them or introducing halos and false detail? Maybe there's a technique or two I haven't tried yet so any tips and tricks gratefully received. Thanks.

Lou Jost
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Post by Lou Jost »

I know you don't like Photoshop but the RAW filter sharpening algorithm does not usually introduce conspicuous haloes (unlike the old Unsharp Mask).

Pau
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Post by Pau »

Maybe some deconvolution methods would do...although don't expect miracles

I've not yet tried this approach but I remember Rogelio Moreno results and discussions:

http://www.photomacrography.net/forum/v ... p?p=134788
http://www.photomacrography.net/forum/v ... hp?t=21618
Pau

TheLostVertex
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Post by TheLostVertex »

Pau wrote:Maybe some deconvolution methods would do...although don't expect miracles

I've not yet tried this approach but I remember Rogelio Moreno results and discussions:

http://www.photomacrography.net/forum/v ... p?p=134788
http://www.photomacrography.net/forum/v ... hp?t=21618
Another thread for reference is https://www.photomacrography.net/forum/ ... p?p=209154

Which might be more practical, since what is discussed does not have the same requirements as 3d deconvolution.

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