You have me on this one. Usually (I'm on a Mac) it's render to disk/image size and dpi/then select from the choices in the pull down.On a Mac, that option that is the only one allowed for you (bmp) would be a pict file on a Mac,which Bryce writes when I do a standard (click the render button)render.Maybe save your bryce file and reboot? Then open the file and go to file/render to disk/save file as/chose file format in pulldown.