A Lumen is a one-of-a-kind cameraless image made by placing objects on light sensitive paper, exposing to light for an extended period of time, removing the object and then fixing the paper. No development is used.
A photogram is a one-of-a-kind cameraless image made by placing objects on light sensitive paper, exposing to light, removing the object and then developing the paper. (year and actual image size shown)