Gaming

Anti-Aliasing Settings Explained: FXAA vs MSAA vs SMAA vs TAA

Anti-aliasing one of the primary graphics settings employed in modern PC and console games. You’ve got the traditional MSAA, SSAA, FXAA, and the shader-based SMAA and temporal techniques (TAA) that have now become the norm. So, what does anti-aliasing do? In short, it gives the image a cleaner look by removing the rough or jagged edges around objects.

No AA
FXAA

Here’s an example of how FXAA (fast approximate anti-aliasing) improves the image quality by reducing the jaggies. Enlarge the images and see how the second one is notably smoother, especially around edges. Here’s another comparison of how AA impacts your game. Here you can see SMAA in action:

No AA
SMAA

The differences are subtle but exist across the entire image. Check the electric pole and the wiring. They lose the teeth on the edges when SMAA is turned on. The buntings and the vegetation also get the same treatment. However, unlike FXAA, SMAA isn’t too strong. It gets rid of the aliasing, without blurring the texture detail.

There are two main types of anti-aliasing techniques:

Traditional Upscaling: These mainly include MSAA (Multi-Sampling AA) and SSAA (Super Sampling AA) which were popular last-gen and for good reason. They produce the best image quality (broadly speaking) but the performance hit is severe. They work by rendering the image at a higher resolution and then scaling it down to fit the native resolution. This essentially makes the entire image more detailed and sharper, scaling down the rough edges in the process but not removing them entirely. Here’s an example:

No AA

Super Sampling renders the entire image at a higher resolution and then scales it down to fit the target resolution. The exact rendering resolution depends on the developer. The image can be downscaled along both the x and y-axis or one of them.

MSAA or multi-sampling uses edge-detection algorithms to detect aliasing (based on contrast differences) and then renders only those parts at a higher resolution. Once again, the amount of sampling varies from 2x to 8x. In most cases, SSAA and MSAA miss transparent textures as most edge detection filters fail to recognize them. Furthermore, they tend to reduce the intensity of aliasing, rather than completely eliminate it.

2x MSAA

Shader based: Shader based AA techniques are more efficient and don’t impact the performance by much. They work by applying a slight blur to the edges, making the image smoother but at the same time reduce the sharpness. FXAA is a good example of how shader based AA gets rid of aliasing but reduces the level of detail by applying a blur filter.

Newer methods such as SMAA greatly reduce the blur intensity while also eating up most of the jaggies. However, it suffers from the same drawback as MSAA: It doesn’t work with transparent textures. The latest and most popular form of AA is temporal anti-aliasing. TAA focuses on removing temporal aliasing or shimmering. It’s most evident in motion. Temporal aliasing is caused when the frame rate is too low compared to the transition speed of the objects in the scene. This makes the boundaries of the objects appear in motion. Here’s a comparison of TAA vs no AA:

No AA

TAA works by comparing neighboring frames (temporally) and blending them to create a cleaner image in motion.

The present frame is rendered along with the geometry and shading, after which it is reprojected on the previous image using the jitter offsets and motion vectors. After that a rectify filter is used to prevent ghosting and the post-processing effects are applied, thereby completing the frame. Similarly, this frame is used for reconstructing (by reprojection) the next consecutive frame, and the process continues.

TAA

Temporal upscaling uses a similar method to upscale lower-resolution images. The core difference is that unlike TAA, alternating pixels are rendered in consecutive frames, and filling the gaps using interpolation and samples from the neighboring frames.

Read more here: NVIDIA DLSS 2.0 vs PS4’s Checkerboard Rendering: Comparing RTX Upscaling with Console Technology

Here’s a comparison of FXAA vs TAA used on the same image:

TAA
FXAA

The main advantages of TAA over FXAA are more pronounced in motion. The “teeth” at the boundaries of the objects appear to be moving when you are in motion in-game. TAA works to smoothen these artifacts while FXAA simply applies a “Vaseline filer” which although effective, produces curvy lines that jump around when there’s a transition in the scene.

Areej

Computer Engineering dropout (3 years), writer, journalist, and amateur poet. I started Techquila while in college to address my hardware passion. Although largely successful, it suffered from many internal weaknesses. Left and now working on Hardware Times, a site purely dedicated to. Processor architectures and in-depth benchmarks. That's what we do here at Hardware Times!
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