Raster
"cam-raster"
(!cam-raster) findraster dup null eq {
  pop
  gsave
    framebuffer setcanvas
    framebuffer newcanvas
    0 0 256 256 rectpath  dup reshapecanvas
    begin
      /Retained true def
      /Transparent false def
      /Mapped true def
      RasterDict (!cam-raster) currentdict put
      currentdict
    end
  grestore
} if