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.