You want to be using a DCT rather than a DFT most of the time with content like this, in order to avoid those boundary artifacts. Compare with the example on th

You want to be using a DCT rather than a DFT most of the time with content like this, in order to avoid those boundary artifacts. Compare with the example on the page http://i.imgur.com/wOVMwxx.png http://i.imgur.com/wOVMwxx.png Source: I once maintained a small C library to do this, but eventually gave it up when it became clear how similar it was to the many existing sinc resampling implementations out there. That said, never stop experimenting.