Converting .djvu publications to other files, including PDF and EPUB or even some images (JPEG, TIFF etc.) is possible and can be done using some specialized converters. Just don't be surprised when the resulting file will be almost 10x bigger than the original in DJVU format.
Convert DjVu image file to Aldus Tagged Image File Format (TIFF) bitmap image.
We have found 2 software records in our database eligible for .djvu to .tiff file format conversion.
Microsoft Windows software - convert djvu to tiff on Windows
One of the best free DjVu viewers and converters
Convert from djvu file format
The tables with software actions are a good pointer for what a certain program does with various file types and often may give users a good hint how to perform certain file conversion, for example the above-mentioned djvu to tiff. However, it is not perfect and sometimes can show results which are not really usable because of how certain programs work with files and the possible conversion is thus actually not possible at all.
A DjVu converter