User Manual/Appendix: Graphic filters
ScummVM offers several anti-aliasing filters to attempt to improve visual quality. These filters take the original game graphics, and scale it by a certain fixed factor (usually 2x or 3x) before displaying them to you. So for example, if the game originally ran at a resolution of 320x200 (typical for most of the SCUMM games), then using a filter with a scale factor of 2x will effectively yield 640x400 graphics. Likewise a 3x filter will give 960x600.
ScummVM uses the following graphic filters:
|Normal||1x||No filtering, no scaling, fastest|
|2X||2x||No filtering, simple pixel duplication (default for non 640x480 games)|
|3X||3x||No filtering, simple pixel duplication|
|Super2xSAI||2x||Enhanced 2xSAI filtering|
|SuperEagle||2x||Less blurry than 2xSAI, but slower|
|AdvMAME2x||2x||Doesn't rely on blurring like 2xSAI, fast|
|AdvMAME3x||3x||Doesn't rely on blurring like 2xSAI, fast|
|HQ2x||2x||Very nice high quality filter but slow|
|HQ3x||3x||Very nice high quality filter but slow|
|TV2x||2x||Interlace filter, tries to emulate a TV|
|DotMatrix||2x||Dot matrix effect|
There is always a speed impact when using any form of anti-aliasing/linear filtering. Filters can be especially slow when ScummVM is compiled in a debug configuration without optimizations. For these reasons, not all backends support all (or even any) of the filters listed above; some may support additional ones. The filters listed above are those supported by the default SDL backend.
Note: The final resolution depends on the original resolution of the game you are playing. For example, the FM-TOWNS version of Zak McKracken uses an original resolution of 320x240, hence for this game the final resolution with a scaler will be 640x480 (2x) or 960x720 (3x). Likewise, games that were originally 640x480 (such as Curse of Monkey Island or the Broken Sword games) will be scaled to 1280x960 (2x) and 1920x1440 (3x).
Select the Graphic Filter
From the GUI
You can configure the Graphic Filter to use globally in the ScummVM Options (see Configuring ScummVM) or game by game, e.g. if you want for a specific game to use a different Graphic Filter than for the other games (see Configuring a game in ScummVM).
Note: When setting a graphic filter in the general ScummVM options it only applies to the games that have a low original resolution (e.g. 320x200 or 320x240). To use a graphic filter with a game that has a higher original resolution (e.g. 640x480) you need to specifically set the graphic filter in the settings for that game.
From the Command Line
To select a graphics filter from the command line, use the '-g' option (see Command line options), e.g.:
scummvm -gadvmame2x monkey2
Finding the best graphic scaler is very subjective and will depend on the user. It also depends on the game as older games tended to use fewer colors and only coarse dithering.