Hardware

What is Nvidia TXAA?

Aliasing is one of the most common imaging dilemmas that make developers scratch their heads. Aliasing is behind the jagged or rough edges that you see on objects in the images. These are also sometimes referred to as the “staircase effect” since the jaggies form what look like staircases. This is due to the pixels that form round objects. Since pixels are rectangular in shape, the pixels that form round objects appear as jagged edges, consequently distorting the image. These jagged edges not only make the images unrealistic, they also strain the eyes, especially for images in motion like in video games.

To counter this effect, developers have come up with various anti-aliasing techniques (AA) like MSAA (Multisample AA), FXAA (Fast Approximate AA), and SSAA (Supersample AA) resulting in cleaner and smoother images. AA techniques wipe out the jagged edges on your favorite video games to make them look more realistic and immersive. Most GPUs now have anti-aliasing settings so gamers can adjust the smoothness of the images until they hit that sweet-spot of smoothness that appeals to their eyes. However, these techniques also have some performance hits. A more efficient anti-aliasing technique significantly improves the image while reducing the impact on the GPU’s performance.

Nvidia Temporal Anti-Aliasing (TXAA)

Nvidia always has gamers in mind, that’s why the leading GPU manufacturer adopted the temporal anti-aliasing technique with a host of improvements over the common TAA. Temporal aliasing is the crawling and flickering that we often observe when playing games. TAA is a type of post-process anti-aliasing technique that deals with temporal aliasing by combining information from past and current frames to remove the jagged edges. Nvidia-exclusive temporal anti-aliasing, the TXAA, involves the same process but has mixed-in other techniques to reduce or completely eliminate image distortions caused by temporal aliasing. The end-result is high-quality images in motion that give gamers a more immersive visual experience. To better understand TXAA, let’s first know more about MSAA, an AA technique where TXAA is based from.

MSAA and TXAA

When a GPU renders an image on your display, it first draws the polygon or the shape of an in-game object, and then it fills the polygon with texture. Spatial anti-aliasing techniques reduce the jaggies before the image is rendered. Generally, anti-aliasing techniques are resource-intensive. Early anti-aliasing techniques like SSAA effectively smoothed out the jaggies but also exhausted much of the GPU’s power.

MSAA is an improvement over earlier spatial anti-aliasing method. Instead of smoothing out the whole image, MSAA only smooths out the edges of the polygons to cut down on the processing power. It, however, does not smooth out textures, which may still result in pixelated textures. MSAA is still one of the most effective and power-efficient methods in reducing aliasing despite its downsides. MSAA has also once been a popular AA method until more advanced techniques have been developed.

Nvidia’s TXAA improves upon the MSAA technique. It has a film-grade quality, combining high-quality MSAA, post processes, and temporal filters similar to those used in CG films to create a smoother, clearer image as compared to other anti-aliasing solutions. It also overlays an anti-flicker filter to reduce the flickering in motion. TXAA maximizes quality while keeping the performance hits at a minimum. In fact, its performance is comparable to that of 4xMSAA but the image quality is equivalent to that of 8xMSAA. TXAA creates smoother, clearer and sharper graphics. Since TXAA is developed for images in motion, its effects are more evident on screens on motion rather than on static screenshots.

FXAA and TXAA

One post-process anti-aliasing method that’s sometimes confused with TXAA is FXAA. Both TXAA and FXAA are proprietaries of Nvidia. Though both are post-processing AA techniques, they work differently and therefore shouldn’t be mistaken one from the other.

FXAA efficiently reduces jaggies from the whole scene by taking into consideration both the polygons and the textures, as opposed to just the polygons of MSAA. FXAA works by comparing the color contrast between two pixels; two pixels of similar contrast indicate that they’re part of the same polygon. Blurring is then applied based on the color contrast of the pixels to eliminate jaggies. This process is also lightweight on the GPU requiring lesser computing power than MSAA.

On the other hand, TXAA is a more complex anti-aliasing technique combining both the supersampling of MSAA and the blurring method of FXAA while blending in Nvidia-customized filters. Because of its complexity, it requires more computing power than its counterparts. The resulting image is crisper, sharper, and softer; much better than what MSAA or FXAA can produce.

Supported GPUs

TXAA also involves hardware anti-aliasing and not all Nvidia GPUs are capable of carrying out such a process. TXAA is available on Nvidia’s Kepler GPUs requiring at least a GTX 600 graphics card or higher. Here’s the current list of Nvidia GPUs that support TXAA:

GeForce GTX 880M
GeForce GTX 780 Ti
GeForce GTX 780
GeForce GTX 770
GeForce GTX 760 Ti (OEM)
GeForce GTX 760 192-bit (OEM)
GeForce GTX 750 Ti
GeForce GTX 750
GeForce GTX 745 (OEM)
GeForce GT 740
GeForce GTX 690
GeForce GTX 650 Ti BOOST
GeForce GTX 650 Ti
GeForce GTX 650
GeForce GTX 660
GeForce GTX 670
GeForce GTX 680
GeForce GTX 660 (OEM)
GeForce GTX 680M
GeForce GTX 660 Ti

Similarly, not all games support TXAA. If TXAA is not compatible with either the GPU or the game, you won’t see it in the settings.

Conclusion

Anti-aliasing techniques have evolved throughout the years to at least reduce, if not completely remove, the unrealistic and distorted effects of aliasing on the game scenes. TXAA is one of the techniques that can produce high-quality images in motion. With a combination of various anti-aliasing methods, including hardware aliasing, and resolve filters, TXAA significantly reduces aliasing compared to other anti-aliasing solutions. TXAA’s final image is much smoother and clearer. Because of its complexity, TXAA is best for gamers who have high-tier gaming hardware. There are however, only a selected number of Nvidia GPUs that support TXAA. If your GPU supports TXAA, it’s time to start playing with the TXAA settings to achieve the image quality you so desire for a more immersive experience.

About the author

Glynis Navarrete

A freelance blogger who loves to write about anything related to technology. Born and raised in the Philippines and worked in Singapore for eight years as Technical Support for a wide range of IT equipment. Took a dive into the world of freelancing and now enjoying doing what I’m passionate about while not losing touch with technology.