img-filtr
Port of straup/filtr to use hawx/img instead of
ImageMagick/GraphicMagick. This means it is slow, and produces different
results, if that sounds like the kind of thing you like install:
$ go get hawx.me/code/img # if not already
$ go get hawx.me/code/img-filtr
$ img filtr dthr < in.jpg > out.png
$ img filtr --help
...
$ img filtr drdl --help
...