XnView Software

I am trying to convert a png file to 'jxr' on 64 bit linux machine. I can convert the png to jpeg. But jxr is giving me an error
Bad output format 'jxr'

Here is the command i use for jxr
nconvert -out jxr test.png
Bad output format 'jxr'

and here is the command for jpeg which seems to be running ...