Attaching Raster Files
Using the Raster Manager dialog, or the Reference group of the Attach tab, you can control the display of raster references in one or more DGN file views.
You can attach a raster reference to a DGN file by selecting , or by selecting the Attach Reference tool in the Raster group of the Attach tab . In either case, the Attach Raster Reference dialog opens, letting you choose the view(s) in which to display the image.
in the Raster Manager dialog