[knc1]

Originally Posted by JJJM

Thanks for your quick and precise reply.

I have exactly typed: k2pdfopt *.djvu -m 0.05 -as- -ws 0.2 -col 1

And it says invalid entry. I have checked examples and I think I did it right but there must be sth wrong. Could you help?

Thanks again.

Try: "Options before Arguments"
k2pdfopt -m 0.05 -as -ws 0.2 -col 1 *.djvu
And if that doesn't work, try it on a single file first.
Note that whitespace and number/position of "-" are significant.