NTSC filters replicate the cables used to connect the system to the TV. They vary in quality, with the lowest being RF, then composite, then s-video and RGB (scart) being the highest quality. Many emulators have NTSC filters built into them. They can also be separately downloaded in .filter format. They were developed by blargg. Other NTSC shaders have been created which do not rely upon blargg's shaders.
The level of blur in RF and composite cables are needed for dithering to blend. S-video, and RGB are too clear to blend dithering. However, snes-hires-blend.cg or mdapt.cg may work fine for the purpose.
Many SNES games were developed with the color distortion from these cables in mind. Such as Chrono Trigger, with shifted values that make blacks look brown and borders look purple, which would be output properly with NTSC colors.
The lowest quality. Very blurry, and subject to static.
Higher quality than RF, but still blurry. This is what most systems used as default.
Much sharper image, though color blur still present.
The highest quality possible. Essentially the same as unfiltered.
Blargg's NTSC shaders are powerful, and well made, but they are very system specific. They are designed for NES-SNES resolutions. Certain games on other systems however, can still make use of them, but not without glitches. For instance, certain PS1 games with have multiple resolutions, some of them will work properly with them (such as 240p), and some won't. This may mean the aspect ratio is horribly messed up for menus, but the main gameplay will look normal.
The standalone .filter files work at resolutions typically found in NES and SNES games, and cause problems when used on systems that use other resolutions. For this reason, there have been attempts at making an NTSC shader that can work on many different consoles and resolutions.
Maister has created an NTSC shader using the .cg format. Insert screenshots.
Many emulators have them built in.
|Genesis Plus GX||Sega consoles|
|Kega Fusion||Sega consoles|