There is an open-source DjVu library as well: http://djvu.sourceforge.net/ http://djvu.sourceforge.net/ Whether that makes the format "widespread" enough for

There is an open-source DjVu library as well: http://djvu.sourceforge.net/ http://djvu.sourceforge.net/ Whether that makes the format "widespread" enough for your use case is of course your decision to make.