Most short run and on-demand printers use a digital press, such as an HP Indigo machine. Essentially these are large, fast, high quality laser printers and the image quality is really good. I get my single sheet The Art of Noticing zeen printed double sided on B2 sized paper by Mixam.
The small scale maquete for this folded zine was printed using an Epson Surecolor SC-P900 ink jet printer and the image quality of the real thing (printed using an Indigo digital press), is very impressive alongside that of the maquete. When pixel peeping there are differences but they are very small and difficult to see and mainly due to CMYK colour space inadequacies.
For another publishing project I am using an A3 laser printer from OKI, once more the image quality is amazing and stands up to that of fine art inkjet printers very well.
