However, as pointed out by other commenters, sinc by itself isn't the greatest support function for enlargement due to the ringing artifacts [0]. Which are pretty visible in your example image [1].
ImageMagick has way more documentation on the choice of resize filter than you'll ever need [2]. But it's interesting reading nonetheless; they settled on different default filters for shrinking (Lanczos) and enlargement (Mitchell).
ImageMagick has way more documentation on the choice of resize filter than you'll ever need [2]. But it's interesting reading nonetheless; they settled on different default filters for shrinking (Lanczos) and enlargement (Mitchell).
[0] http://www.imagemagick.org/Usage/filter/#ringing
[1] http://i.imgur.com/JDPvHjf.png
[2] http://www.imagemagick.org/Usage/filter/