Basic Lanczos is a bit soft for both shrinking and enlarging.
Sharp variant fares significanlty better when shrinking, but has even more ringing than basic, which is especially visibie when enlarging high-contrast images.
To not have to deal with the problem use Mitchell-Netravali filter for enlarging instead as it is a reasonable compromise between artifacting and sharpness with little distortion.
Possible future improvements: factor bits per color and contrast when selecting resize filter
Basic Lanczos is a bit soft for both shrinking and enlarging. Sharp variant fares significanlty better when shrinking, but has even more ringing than basic, which is especially visibie when enlarging high-contrast images. To not have to deal with the problem use Mitchell-Netravali filter for enlarging instead as it is a reasonable compromise between artifacting and sharpness with little distortion.
Possible future improvements: factor bits per color and contrast when selecting resize filter