QPixmap/QImage How to enlarge a picture

Hello,
The scaled function of the QPixmap class works fine to shrink a picture but is not very good to enlarge a picture. For instance, let's say my thumbnail is 100X100 and I would like to double it; the final picture is of pretty low quality.
Is there a function in Qt to make that extrapolation better?
Thanks

You will always lose out on quality when enlarging pixmaps. The best way I can come up with is either DIY, or ensure that you've set the transformation mode to SmoothTransformation in the scaled() call.