Please improve resampling algorithm

[Betterbird]

Some resized images have poor quality, even at best quality setting, I'll attach an image that shows the effect.

Coincidentally, someone wrote this in a review at ATN yesterday:
It works, but the quality of the resized images is terrible, even if using high quality source. Rasters are easily visible. It would be much better if the plugin would be used bicubic resampling.

GIMP for example gives much better results with its LoHalo algorithm.