A holoprojector was a device that could record, send, receive, and/or display holograms. Holoprojectors came in various sizes. Low-quality holoprojectors did a poor job of rendering colors accurately, as the fed everything through a strong blue filter.
Approximately 30 years after the Battle of Endor, the technology of holoprojectors became sophisticated enough to allow the user to be seen in full color, with no filters or scan lines visible. A known individual to use this technology was the First Order's Supreme Leader Snoke.