I have a lot of images downloaded years ago in djvu format, which sometimes refuse to open and other days will, so I am going through the ones I want to keep and downloading them again but as jpgs.before my sub runs out. I have just noticed that although the image looks exactly the same quality, the equivalent jpg is much larger. E.g one I have just saved is 707kb, whereas the djvu was only 213kb. So I'm going to need more than three times as much storage space.
Does anyone know if there is a way to make the jpg smaller without losing quality?