Krita and scaling

[Boudewijn Rempt]

On Thursday 19 August 2004 01:30, Michael Thaler wrote:
> Hello,
>
> first, there is definitely a bug in the Krita painting code which gets
> triggered when an image, that is larger then the screen resolution, is
> scaled down. I made two screenshots:
>
> http://www1.physik.tu-muenchen.de/~mthaler/krita1.jpg shows the original
> image which is 1600 x 1200 pixels and does not fit on my screen.
>
> http://www1.physik.tu-muenchen.de/~mthaler/krita2.jpg shows the image
> scaled down to 800x600 pixel with Boudewijn's old algorithm. It looks like
> certain tiles are not painted.

I know Casper is working on the tiling code, trying to get rid of the direct 
access to tiles, so I guess we won't be debugging this right away. It's quite 
complex to work with tiles, cobbling over the edges and everything.

>
> I also ported the scaling code from the Graphics Gems III book Adrian
> mentioned, to Krita. I got it working and the results are very nice:
>

Nice indeed!

> http://www1.physik.tu-muenchen.de/~mthaler/krita3.jpg shows the original
> image.
>
> http://www1.physik.tu-muenchen.de/~mthaler/krita4.jpg shows the image
> scaled uo to 145% of the original image.
>
> http://www1.physik.tu-muenchen.de/~mthaler/krita5.jpg shows the image
> scaled down to 46% of the original image.
>
> I used the Mitchell filter to produce these screenshots, it is a cubic
> interpolation filter.
>
> Actually the scaling routine has still some bugs: the column on the very
> right and the lowest row are black. Also the code is quite complex right
> now and I want to clean it up before I post the patch to the list. Maybe I
> have time for that tomorrow evening or on Friday,
>

I hope so -- I'm really looking forward to it.

-- 
Boudewijn Rempt | http://www.valdyas.org/fading/index.cgi
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