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+--- Thread: Resize image too blurry (down scale) (/Thread-Resize-image-too-blurry-down-scale)
Resize image too blurry (down scale) - lyjim - 02-19-2026
Is there any way to deal with this?
Here's an example, resize to 25%.
Gimp - blurry. (if choose None, will get terrible aliasing)
Windows Paint - not blurry (but not support alpha).
Original image (cannot attach, said too large): https://1drv.ms/i/c/cfd39d12afb55641/IQBPt459SUJmRaSOJrCEh7hpAWEgLu_ti3phaJss9bfcMkA
Result-Gimp: https://1drv.ms/i/c/cfd39d12afb55641/IQCKVgskn6RcQa9VzI2AR6AZARUj-U6-NZBmnceDmBBTfrU
[attachment=14256]
Result-Windows Paint: https://1drv.ms/i/c/cfd39d12afb55641/IQABxwSGkPN9SKD_i0dYkvlUAUJcoW7K7PVKgEO4nLDEi9Y
[attachment=14257]
Look at the face and hair.
edit:attachment seems didn't display.
RE: Resize image too blurry (down scale) - rich2005 - 02-19-2026
The scaling algorithm to use is LoHalo.
quote: LoHalo method: when you downscale an image thats less than a half of the original size
It looks to me that the MSPaint scale also incorporates an automatic degree of sharpen. As a comparison.
(1) Scaled with Gimp 3.0.8 LoHalo
(2) Your MSPaint example. I can see a small amount of "fringing" that forehead detail for example.
(3) A default value unsharp mask applied to (1). There are other (possibly better) sharpening tools, I often use one of the gimp_gmic_qt filters.
[attachment=14258]
RE: Resize image too blurry (down scale) - sallyanne - 02-19-2026
There is a new filter in version 3 of gimp under enhance, to sharpen which doesn't do a bad job called sharpen deluxe.
I downloaded your file, sharpened but it wont save/export. My antivirus doesn't like it.
(Weird that it let it download but wont save from gimp)
RE: Resize image too blurry (down scale) - lyjim - 02-19-2026
(4 hours ago)sallyanne Wrote: There is a new filter in version 3 of gimp under enhance, to sharpen which doesn't do a bad job called sharpen deluxe.
I downloaded your file, sharpened but it wont save/export. My antivirus doesn't like it.
(Weird that it let it download but wont save from gimp)
.png image file is unrelated with virus in general situation, this may just because your settings prevent editing "downloaded from web" file which Windows add a mark.
RE: Resize image too blurry (down scale) - rich2005 - 02-19-2026
(4 hours ago)sallyanne Wrote: There is a new filter in version 3 of gimp under enhance, to sharpen which doesn't do a bad job called sharpen deluxe.
...snip...
That is an addon - a GEGL remix of wavelet-decompose see: https://github.com/LinuxBeaver/GEGL-GIMP-PLUGIN_Sharpen_Deluxe/releases/tag/GimpSharpen
my usual go-to is the gimp_gmic_qt filter FFT Sharpen
RE: Resize image too blurry (down scale) - lyjim - 02-19-2026
(6 hours ago)rich2005 Wrote: The scaling algorithm to use is LoHalo.
quote: LoHalo method: when you downscale an image thats less than a half of the original size
It looks to me that the MSPaint scale also incorporates an automatic degree of sharpen. As a comparison.
(1) Scaled with Gimp 3.0.8 LoHalo
(2) Your MSPaint example. I can see a small amount of "fringing" that forehead detail for example.
(3) A default value unsharp mask applied to (1). There are other (possibly better) sharpening tools, I often use one of the gimp_gmic_qt filters.
I check Gmic and found a "Scale Down" filter in Gmic, use Amount=10 and Darkness=0, result seems better, but still cannot get as clear as Windows Paint do.
RE: Resize image too blurry (down scale) - rich2005 - 02-19-2026
(3 hours ago)lyjim Wrote: .
I check Gmic and found a "Scale Down" filter in Gmic, use Amount=10 and Darkness=0, result seems better, but still cannot get as clear as Windows Paint do.
The gmic Scale Down has a section for sharpening, bump that value up. Keep the initial pre-blur on - it used to be in old gimp you had to do that yourself, the new gimp Lo/Hi/ have that built in. If you find a suitable mix of settings, then save that as a "fave" - saves a bit of time when applied again.