Qt-interest Archive, September 1998
Re: QImage::smoothScale problem
Message 1 in thread
"Hubert W. Schreier" wrote:
> QImage i = image.copy(x, y, s, s);
> QImage scaled = i.smoothScale(200, 200);
>
>For some values of s, scaling messes up the image completely. 25 does
>not work, 24 does, 27 does not.
The bug is in QImage::copy(). Fixed in Qt 1.41beta - please test it out.
>Furthermore, scaling is not really smooth. In the documentation, I could not
>find what the smooth refers to. Does this function use some smoothing filter
>to avoid aliasing when downscaling, or is it meant to produce a smooth, i.e.
>not pixelated image when upscaling?
It the standard pixel sub-sampling algorithm.
>Are there any other QImage/QPixmap functions for scaling, and what
>interpolation methods do they use?
QPixmap::xForm() - but it uses no interpolation.
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