If you use Linux, I believe it's easy to convert images to a DjVu file.
Please use img2djvu (https://github.com/ashipunov/img2djvu) to convert images to DjVU.
All the images in the folder should be in order.
$ img2djvu -d300 ./your_folder_containing_images
And combine several DjVu files to a single file <doc.djvu> as
djvm -c doc.djvu 2011.djvu 2013.djvu 2013-100.djvu
2011.djvu 2013.djvu 2013-100.djvu are files to be combined.