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Index › Programming Questions & Help › Programs › Image resizing causes pixelation/blurring
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Image resizing causes pixelation/blurring (Read 509 times)
glenn
Image resizing causes pixelation/blurring
Apr 9th, 2008, 8:47pm  
Hi
I'm trying to use bitmaps of fonts and randomly scaling them onto the screen, from the orginal size right down to about 5 x 5.
However the image resizing isnt the best, whether using P3D or JAVA2D the results when scaling from say a 500 x 500 bitmap of a letter down to say 20 x 20 are really poor.  I've tried all sorts of ideas, I could go the vector outline way, but I'd rather find a better way of rescaling bitmaps all together.

Does anyone know of any libraries/hacks that can do image resizing as good as photoshop?

Thanks!

Glenn.
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movax
Re: Image resizing causes pixelation/blurring
Reply #1 - Apr 9th, 2008, 10:52pm  
The best image downscaling routines use frequency based filtering to achieve their results.  I.e. removing a lot of the high frequencies that become noisy moire-junk when shrunk down.  So, using a 2D FFT of the image is how the big boys do it, however there is an easy way.

Just blur the image before scaling it down.
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glenn
Re: Image resizing causes pixelation/blurring
Reply #2 - Apr 9th, 2008, 11:09pm  
Thank you!

Has helped a lot,
shouldn't be too much trouble to work out an algorithm to blur the source image in ratio to how small it's being scaled.
At least I know there's a solution!

The FFT thing sounds sexy, I'll look into it too,

Cheers,
Glenn.
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fry
Re: Image resizing causes pixelation/blurring
Reply #3 - Apr 11th, 2008, 7:38pm  
with JAVA2D, smooth() improves image smoothing as well:
http://processing.org/reference/smooth_.html

with P3D, you can use hint(ENABLE_ACCURATE_TEXTURES)
http://processing.org/reference/hint_.html
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glenn
Re: Image resizing causes pixelation/blurring
Reply #4 - Apr 12th, 2008, 8:29pm  
I didn't notice any difference with the hint swicthed on, and I would always use smooth() with java2d anyway, but movaxs solution is working out though,
thanks,
G.
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