Last Update: 7/22/2021
Origin has an X-Function named insertImg2g that is used to insert images into graph windows. While implemented primarily to support Origin's Google Map Import App, you can use it on its own to insert a raster image into the background of any graph and lock the image to the containing layer's scales.
dlgfile g:="*.PNG"; // can substitute any supported raster file type for .PNG
insertImg2g type:=img xyp:=2;
Keywords:raster, insert image, layer and scales, object attachment