Sharpening

[Marpel]

A general query, unspecific to PWP.

I took a quick survey, and found PS has - Sharpen, Sharpen Edges, Sharpen More, Smart Sharpen and Unsharp Mask. PWP has - Advanced Sharpen, Bilateral Sharpen, High Pass, Sharpen, Sharpen More and Unsharp Mask.

As a general statement, I suspect users employ one/some/all of these techniques for the simple purpose of making an image look sharper. Other than Deconvolution Sharpening, it appears that the purpose of these methods is to highlight edge contrast.

And there are a plethora of scripts/actions touted by the experts in using some form/combination of those methods, to confuse things even more.

So, my questions are,
- Why are there so many ways offered to do the same thing and why would I use one on an image and another on a different image?
- And if the purpose is to arrive at an optimally sharpened image, is one of these methods the best?
- I realize an image requires different sharpening for different end results (web as opposed to print etc), but why can't the same (best method) be used for all that?

Methinks (in my layman's mind) it would be easier for a user to be given the single best method and then expend all energy on perfecting the settings of that one method, rather than fussing with all the others in trying to obtain a perfectly sharpened image.

Can someone shed a bit of light?

Marv

[jsachs]

Mostly the reason there are so many is historical - Sharpen and Sharpen More are the oldest and simplest as they just look at the nearest 4 or 8 neighboring pixels. Next came Unsharp Mask which is also quite old. High Pass is not really sharpening but is used as part of some PS workflows.

Personally, I use Bilateral Sharpen the most as it is relatively easy to use, can sharpen on multiple scales at once, and has good halo suppression. Occasionally I use Sharpen or Sharpen More to add back a little sharpness after resizing an image.

Using Advanced Sharpen is a lot of work although it can also do some noise reduction. I almost never use it.

I am not really familiar with PS Sharpen Edges or Smart Sharpen, and there are countless sharpening plug-ins that promise one thing or another.

[tomczak]

Advanced sharpen is pretty labour intensive but it has quite a control over what's being done to the image (and what's not). Den may agree... That may be the one to choose for something important, printed large. The final sharpened image look is not quite the same as after Bilateral Sharpen.

One way to see what those different sharpening methods do, and what halo-suppression and thresholding do, is to use a test image like the one below. It's not the only sharpening test image, but I like it because it shows a range of edge physical thicknesses as well as contrasts, all in one image. It's artificial obviously, but it allows me to better understand what different sharpening controls do when I test them on it.

viewtopic.php?f=5&t=1051

[Charles2]

Maybe the user is not given "the single best method," but I agree that a user should be able to employ one best procedure, the best he knows (which may evolve!). When I begin a raw file in Raw Therapee, I use its RL Deconvolution. The radius is important: 0.8 - 1.0 for Bayer CFA, .04 - 0.5 for Fuji X-Trans. But for each image, you must find a good amount, just as with PWP amount sliders. Then in PWP I use Bilateral Sharpen at radius 80 and a small amount for local contrast, as Jonathan described recently.

For a print, I additionally do Advanced Sharpen and the rule of thumb: push the sharpen just to where it intrudes.

[tomczak]

I was trying to pinpoint why I like AS results better than BS.

One aspect may have to do with the AS ability to set smooth, soft roughness threshold range between what's sharpened/blurred and what's not (white and black sliders under the roughness histogram).

The BS equivalent of that, with a stretch, are Blur Threshold and Sharpen Threshold, but they don't collaborate as smoothly visually as AS.

[Marpel]

Thanks to all for the replies,

I think I will restrict myself to understanding Bilateral and perhaps Advanced, in hopes of getting the best from them.

For the longest time, I have had sharpening turned off in the raw program (Nikon's NX-D) and after processing to tiff, I do a light sharpening in Focus Magic. The issue then becomes what is the best sharpening after that point. I have tried a myriad of sharpening techniques in PWP and PS, but as already mentioned, it becomes difficult to identify the best of the best.

Marv