It is well known that modern video adapters no longer perform dithering in 16-bit modes, which causes banding to appear.

I just experienced a curious Glitch that rendered Half-Life in true color. I tried normal Half-Life and the Uplink demo level usign the OpenGL renderer. No mods, no steam, no nothing.

Reference with dithering, ATI something.

nVidia GT 610.

nVidia GT 610 in True Color.

The glitch occurs when the video apdater gets in a state where it cannot switch display modes after a long uptime. It is fixed by a reboot, and not interesting as a problem. Trying to switch the mode via Display Properties gives a message that a reboot is required. The Half-Life 640*480 main menu appears in the corner of the screen, and later the game seems to inherint the video mode of the Windows desktop. It was clearly visible on dark doors, or these red walls.

I had to take a screenshot with IrfanView, because Print Screen copied a corrupted picture. That is why it is not exactly aligned to the previous frames.

This experience suggests that it might be possible to upscale some games "by driver" in a relatively simple manner, kinda like we can add anisotropic and antiliasing. I would of course still prefer dithering sparkle to make low detail textures appear richer.