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Better Resizing Process?

(Running GIMP 2.8.10 on Linux Mint 13. Camera is a Kodak EasyShare C713 that I got for free as a workplace bonus a few years ago.)

I have noticed that Gwenview (the default KDE image viewer) uses a scaling process which produces better results than GIMP in many situations. The attached file shows a cropped comparison between the results of resizing an image in GIMP (left) and Gwenview (right). The Sinc/Lanczos3 routine was used in GIMP; Cubic and Linear were also tried but did not work better. The difference is most obvious in the window screen. Similar effects occur with other objects prone to aliasing issues, for example architectural subjects with lots of straight lines (window grids, tiled roofs etc.). What I've ended up doing most of the time is doing everything in GIMP except the scaling, then exporting the image, opening it with Gwenview, scaling it there, and saving it again, which is a bit cumbersome.

What process is Gwenview using to scale images, and would it be possible for A) GIMP to add it to the available Image/Scale Image options, or B) some wizard here to write a plugin that would do the same thing?

Or, if I am missing some setting in the GIMP preferences that would improve this, please give me the heads-up.

Thanks!

It would be helpful to see the original file that is being scaled.

Added an image at the original resolution. Nothing special about the image itself; the effect of scaling on the window screen just seemed like a good example. Thanks!

Have you tried some of the various pre blur re sizing filters?

-Rod

Can you point me toward specific scripts here that I could try? I have tried a couple of scripts and plugins that resize in steps. I would say that the result is sometimes a bit better than the default Scale process, but never as good as the Gwenview example. I imagine tight grid-like textures like this are probably the hardest thing for a scaling routine to handle without that kind of obvious aliasing, though.

Check this posting at GimpChat.com. :)
http://gimpchat.com/viewtopic.php?f=9&t=7258&p=92490#p92490

-Rod

Hmm... I see the idea. It looks like it does help a little, but it basically softens the moiré effect a little rather than suppressing it as much as Gwenview's process somehow does. I've posted a third image above, scaled using this script. Thanks!

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