I think the assumption is this is continuing on from the graphic novel story rather than the film's story. However, the film is pretty close to the graphic novel and most significantly differs in how the ending plays out. So even if you have just seen the film you will probably mostly still understand enough....
And on that note I don't think you need to have seen or read anything prior to this. While it's designed to be a sequel show it is also designed for newcomers to the franchise. There's not many returning characters and I am sure the few there are will be given full context.
