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Gimp 2.10 has unified the sharpen and unsharp mask filters that were two separate filters in earlier versions (both located in the Filters > Enhance submenu).

I can imagine that from an "engineering point of view" the move seemed to make sense, because they worked using a similar concept. However the new unified filter is not without disappointments. Allow me to describe:

The sharpen filter in v2.8

I found that sharpen worked well only for relative smallish images, like below ~ 2000px longer side, or so, and when cranked up to a high value, it provided results some may consider quite rough, not fit for professional publishing.

But I'm not a professional publisher. What I needed it for was sharpening (often low resolution and quality) images of various machinery and technical products, in order to observe and understand how these complex structures worked.

For this purpose it did not matter if the result looked a bit rough.

The unsharp mask filter in v2.8

The way I used this filter was a bit comparable to how the Clarify effect/filter worked in some earlier version of PaintShop Pro that I had the opportunity to try out. This clarify effect differentiated separate areas in a picture, often, for example, subject versus background, or overlapping objects, and made them stand apart more (so the eye perceived the spatial "depth" much easier, in effect, in an instant).

I used Gimp 2.8's unsharp mask filter to get somewhat comparable results by setting its Radius to around 100px and even above (combined with only a mild value for Amount).

I often used this trick also for images of landscapes.

The "unified" Sharpen (Unsharp Mask) filter in v2.10

Sharpening seems to have lost some of its edge: like it now prioritizes publishing-industry oriented quality over achieving extreme visual revealing power.

My unsharp mask trick for large areas now delivers unacceptable results, because it deposits so much dark into smaller-scale, midtone-but-in-a-brighter-context areas.

In the new, unified filter, increasing the Radius increases not only the distribution of the effect — the area that is impacted — but also the intensity: darks get even darker. This should however be be the responsibility of the Amount slider.

So now, if I reduce the Amount, the results do not seem to get applied evenly: even if I tone down the effect to be barely noticeable in most of the image, the darkness of small pockets persists disproportionally: crevices and small shadowy areas remain to stand out painfully dark and ugly from the rest of the image.

I never had such a challenge with the old Unsharp-mask filter.

Can I get back the old filters?

Do some plugins exist that would bring back the algorithms of the old filters? Or what other action can I take to benefit from the effects of the older variants?

I use Ubuntu 20.04 (in case it matters), but if you know something specific to Windows 10, I'd be interested to hear that too.


Update:

Following up on @BillyKerr's answer, I dug deep enough to find out that on Ubuntu 20.04, the standard available Gimp version is 2.10.18, this is the one I was using.

Now I have installed the "flatpak" variant too (it's like "Portable Apps" for Linux), which happens to be newer: 2.10.24.

In 2.10.24, an addition is present: the Blending options section is now available in the filter window, and digging in it, there is a choice between Default and Legacy. This looks exciting, but to be honest, in the first quick experiments I could not spot the difference between them. Anyways, I expect, if this would work, then this would offer a relief only for the Unsharp Mask challenge, as the new unified filter seems to be based on that.

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You may be able to extract the old filter from an older copy of GIMP, but no guarantee it will still work in newer versions of GIMP. You can download old stable versions from the GIMP website: https://www.gimp.org/downloads/oldstable/

Edit: Further to comments, the sharpen filter for GIMP 2.8 on Linux seems to be located in the following folder: gimp-2.8.22\plug-ins\common\sharpen.c So you'd need to copy that file and paste it in the corresponding folder in GIMP 2.10. Obviously I've no idea if this will actually work. Perhaps it's worth a try. I'm no Linux expert though.

Anyway, I'm not convinced you can't get almost exactly the same effect from the new unsharp mask filter. Obviously it requires manual tweaking and there are more sliders to deal with, but after you've got the settings, you could just save it as a preset, then reload the preset when you need it.

After having a look at the old filter example here, and using the images on that page, here's a screenshot showing the new filter and the result is almost identical. I adjusted the settings until it looked as similar as possible. Then I saved a preset called "Old Sharpen" to use as a baseline. To adjust further, as per the old filter, use the "Amount" slider to adjust the total amount of sharpening.

Here's the example

enter image description here

Remember if you're applying sharpening on images intended for the web, to always view them at 100% zoom, and obviously first rescale the image to the actual size that is going to be used. Trying to apply sharpening on larger images (zoomed out) is probably where you're coming unstuck.

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  • "You may be able to extract the old filter from an older copy of GIMP" — how is that done? And how is it added to my current, newer version? – Levente Apr 1 at 19:16
  • Also, I have found the older stable releases downloads on the Gimp website, but they don't help me much because 1.) I'm not on such a level where I could "build programs from source", 2.) Those old installs are system-wide, so they would still need old dependencies installed OS-wide like Python 2, and other old runtime environments, that I would rather avoid. The "flatpak" format would be more viable, because its apps are self-contained (it's like "Portable Apps" for Linux), but following the help, I could install only the latest version (2.10.24), not 2.8. – Levente Apr 1 at 19:18
  • Well it'll be in a plugin folder in your GIMP directory, you'd need to try to find it. Sorry, I don't have an old copy to check, then copy and paste it in the corresponding plugins folder in GIMP 2.10. The situation with Linux could be more complex. Sorry, I'm no Linux expert. Only a graphic designer ;) To be honest I think it would be far easier to use the preset option. Doesn't that work for you? – Billy Kerr Apr 1 at 19:18
  • Could you point the corresponding files out here please? The 2.8.22 file tree: gitlab.gnome.org/GNOME/gimp/-/tree/GIMP_2_8_22 – Levente Apr 1 at 19:23
  • I use GIMP on Windows only. The folders in Windows look nothing like that. Sorry. – Billy Kerr Apr 1 at 19:27

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