neural-styleのエラー

libpng warning: Application built with libpng-1.4.12 but running with 1.6.28
/Users/shinriyo/torch/install/bin/luajit: /Users/shinriyo/torch/install/share/lua/5.1/image/init.lua:176: [write_png_file] png_create_write_struct failed
stack traceback:
    [C]: in function 'save'
    /Users/shinriyo/torch/install/share/lua/5.1/image/init.lua:176: in function 'saver'
    /Users/shinriyo/torch/install/share/lua/5.1/image/init.lua:442: in function 'save'
    neural_style.lua:271: in function 'maybe_save'
    neural_style.lua:293: in function 'opfunc'
    /Users/shinriyo/torch/install/share/lua/5.1/optim/lbfgs.lua:211: in function 'lbfgs'
    neural_style.lua:303: in function 'main'
    neural_style.lua:601: in main chunk
    [C]: in function 'dofile'
    ...riyo/torch/install/lib/luarocks/rocks/trepl/scm-1/bin/th:150: in main chunk
    [C]: at 0x010be13350

が出た。

https://github.com/jcjohnson/neural-style/issues/138

に似た人。

-output_image ~/Pictures/test.pngを-output_image ~/Pictures/test.jpgにした直るのか？ 違う拡張子だめなのかな？ そもそも-output_imageのオプション書いてないのだが・・。