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Topic: How To Use The Fractal Interpolation Plugin?

Could somebody tell me, how I can adjust the resizing amount of the Fractal interpolation Plugin? Why does this additional method not appear in the methods of the image -> resize dialogue?

Thank you for your support!

Kind regards, Norbert

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Re: How To Use The Fractal Interpolation Plugin?

You cannot set the size - it always doubles the image in both directions. If you want it less than doubled you can use  the Image | Resize dialog to decrease the size afterwards.

Plugins cannot modify existing features, only add new ones. That is why it does not appear in the same dialog.

Michael Vinther

> software developer <

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Re: How To Use The Fractal Interpolation Plugin?

Hmm... I didn't even realize that was a resizing plugin. I saw it on the site, but assumed it was for opening fractal compressed files.

It seems to work great on most images, but flubs on images with text. Somehow, it splits lines and inserts spaces in them.
Examples:
http://allspark.net/cypherswipe/RavePixelX2.png
http://allspark.net/cypherswipe/RaveFracta...talLambda05.jpg
In this example, the person in the image was actually improved, but take a look at the word "musica" in the upper right.
http://allspark.net/cypherswipe/CardOriginal.jpg
http://allspark.net/cypherswipe/CardFracta...talLambda02.jpg
In this one, nearly all the text has been affected.

What I'm wondering is if this is an inherant behavior of the fractal process, or if it can be avoided by adjusting some setting or doing some other processing before enlarging? I have tried different smoothing/lambda settings, but they only affect how blurry the image is.

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Re: How To Use The Fractal Interpolation Plugin?

Producing these thin vertical or horizontal lines seems to be a problem with my resizing algorithm. It is simply not suited for handling text. I have noticed it before, but have not found a way to avoid it.
But apart from that this is one of the best algorithms I have ever seen for enlarging high quality photos and keeping the sharpness.

Michael Vinther

> software developer <

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Re: How To Use The Fractal Interpolation Plugin?

No argument there. The next closest would be bicubic resample followed by some heavy sharpening, and that always results either in an image that's still fuzzy or one with a lot of artifacts from the sharpening process. In certain cases, the fractal enlarged images are even an improvement over the original images.

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Re: How To Use The Fractal Interpolation Plugin?

An updated version is now available with a filter for reducing the problem with the thin horizontal/vertical lines. This leads to a significant improvement with many images.

Michael Vinther

> software developer <

Re: How To Use The Fractal Interpolation Plugin?

The new version is much better.
Here is the image I started with:
http://allspark.net/cypherswipe/fractal-original.png
In this one I used the old plugin with lambda at 0.5, you can see the thin lines all all the vertical lines:
http://allspark.net/cypherswipe/fractal-old.png
In this one I used the new plugin with lambda at 0.5 and the artifact remover at 8:
http://allspark.net/cypherswipe/fractal-new.png
For comparison purposes, I enlarged the pic to 200% using bilinear and wiener-6:
http://allspark.net/cypherswipe/fractal-bilinear.png
http://allspark.net/cypherswipe/fractal-wiener6.png

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Re: How To Use The Fractal Interpolation Plugin?

In general the algorithm works best for photographs, but it seems that the updated version can also handle drawings. Thanks for the excamples.

Michael Vinther

> software developer <