# Filtering

ddraw default |  | The normal mode, where the primary surface is stretch-blitted to the window surface.
Fast 2X Bilinear | BILINEAR2XFILTER | Activates a simplified filter that scales each pixel twice, interpolating the colors of adjacent pixels. The default window size is double the resolution of the virtual screen. If you choose a different size, the surface is scaled to fit into the client area, but this noticeably slows down the blit operation.
Full Bilinear | BILINEARFILTER | Activates a bilinear filter to scale the DirectDraw primary surface to the window client area. When this is used with GDI games, it activates GDI internal filtering for better scaling.