I've looked at the results from the image scaling code and its very poor quality. I've looked around to see if theres something we can do to improve the quality and/or speed of the process. I've come with a few ideas.

This website talks about the Bresenham line algorithm and how it can be applied to image scaling. Supposedly it has a good trade-off between speed and quality, using integer math instead of floating point to add the process. It includes C code examples of how it can be implemented. Website is here: http://www.compuphase.com/graphic/scale.htm

I also found some old resizing code from ~2003 in an obscure image library that appears to be licensed under LGPLv2. In the stimg.c source file, under the function 'stimg_resize' the code can be found. It appears to work on pixels in the same manner that PImage does, 8 bit channel array in the order of RGB with an optional A channel. I tested its performance and it seems to be very good quality when you request the "anti-aliasing" mode, and even without it. But I am unable to gauge how fast it is in real-time if that is a concern. This is the latest version I was able to find. The download url is here: http://homepage3.nifty.com/slokar/stimg/stimg-0.1.0.tar.gz

Both of these seem like promising options because in all honestly the current scaling code leaves much to be desired. The quality is too poor for theme designers to use.