Scales the image to a new size.
Method for scaling is rather complex;
the image is transformed via a cosine transform,
and then resampled back.
This gives a quality-conserving upscale,
but the algorithm used is n*n+n*m, where n
and m is pixels in the original and new image.
Recommended wrapping algorithm is to scale
overlapping parts of the image-to-be-scaled.
This functionality is actually added as an
true experiment, but works...