DjVu is a format developed internally at AT&T that is both smaller and better in quality than PDF format. According to Wikipedia, this format has been designed primarily to store scanned documents, especially those containing a combination of text, line drawings, and photographs.
Pdf To Djvu GUI is a free opensource tool for both Windows and Linux that can quickly convert Pdf files to Djvu format in one go. In short, it is a Pdf To Djvu Document converter. Just load the PDF files, select the resolution and few general settings and click Generate DJVU.
Conversion will take some time, depending on the length of file and the settings you have selected. You don’t need to select any Output destination, since all converted files be will saved in the same location where the original Pdf file is located. It is completely portable and no installation is required. Enjoy!