Well the only way to have really sharp 2D would be a 2D filter called 2xSai. You can test that filter in many emulators like zsnes and mame.
There are four types of 2xSai : 2xSai, 2xSai super and those two as "vba" mode, that look even better.
To have the best view of those filters I recommend trying them with Final Burn Alpha, a Cps1, 2, neogeo and others emulator.
At this moment it is the emulator proposing the most 2D filters I've seen, in the latest release. Maybe some revision of mame offers as much 2D filters.
By the way 2xSai works great on textures too, you can test it with playstation 1 emulators (Epsxe if I recall correctly).
There are four types of 2xSai : 2xSai, 2xSai super and those two as "vba" mode, that look even better.
To have the best view of those filters I recommend trying them with Final Burn Alpha, a Cps1, 2, neogeo and others emulator.
At this moment it is the emulator proposing the most 2D filters I've seen, in the latest release. Maybe some revision of mame offers as much 2D filters.
By the way 2xSai works great on textures too, you can test it with playstation 1 emulators (Epsxe if I recall correctly).