Texture filtering

Texture filtering refers to the methods used to smooth the textures of a 3D model. Every home console after the Nintendo 64 is able to do it, including every modern PC and Android device. This makes it useful in emulation, where it can be applied to emulators for consoles that did not originally have it through various emulators that support it.

This article is about smoothing techniques that may be present even on original hardware. For the process of replacing textures to improve their visual fidelity or other aesthetic reasons, see Texture Packs.

Console	Texture Filtering	Types of filtering
Super Nintendo	✗
3DO	✗	?
Atari Jaguar	✗
Sega Saturn	✗
PlayStation	✗
Nintendo 64	✓	Three-sample
Sega Dreamcast	✓	Bilinear, trilinear, anisotropic
PlayStation 2	✓	Bilinear, trilinear, Anisotropic
GameCube	✓	Bilinear, trilinear, anisotropic
Xbox	✓	Bilinear, trilinear, anisotropic
Nintendo DS	✗	?
PlayStation Portable	✓	Bilinear, trilinear
Wii	✓	Bilinear, trilinear, anisotropic

Texture Filtering Algorithms

These methods determine how a texture is sampled and displayed on a 3D model in real-time. They are generally native to original hardware or forced via emulator enhancement settings.

Filtering type	What it does	Pros	Cons
Nearest neighbor	The GPU picks the color of the single closest pixel in the original texture.	Preserves sharp pixel-art style. Lowest computational cost.	Causes "shimmering" or "aliasing" in motion. 3D textures look "blocky" up close.
Bilinear	Averages the color data of the 4 closest pixels to create a smooth transition.	Looks better than nearest neighbor for 3D games. It's the least system-intensive form of texture filtering/scaling.	Can look "blurry," especially on low-resolution textures. Does not look good for 2D sprites.
Trilinear	An extension of Bilinear that interpolates between mipmaps (different resolution versions of the same texture).	Eliminates visible "lines" or "bands" between texture quality levels in the distance.	Still produces blurriness at sharp viewing angles.
Anisotropic (AF)	Enhances texture quality on surfaces viewed at oblique angles (like floors or walls).	Drastically improves clarity for distant textures. Modern GPUs handle this with almost zero performance loss.	Not available on older legacy hardware.

Texture Scaling Algorithms

For smoothing shaders, see Shaders, presets and filters#Smoothing.

These are enhancement algorithms (often called "upscalers") used by emulators to increase the resolution of textures to look better on modern displays.

Scaling Algorithm	What it does	Pros	Cons
HQx	A texture scaling algorithm. Scales up a nearest-neighbor version of the texture and fills in the gaps with copies of the pixels next to said gaps.	While it is inherently destructive, some games (eg. Yoshi's Island) may benefit from this filter, as it preserves the cartoony look.	Artifacts are common. Curves and slopes that aren't 45° look jagged compared to everything else. The finer details of the textures/sprites might be obscured by bad edge detection. Posterization is very common. There are deposterization filters in some emulators (e.g. PPSSPP) that can aid this, however. Worse at some things that xBR excels at.
2xSaI	A texture scaling algorithm. Scales the texture and fills edges in with a mixture of pixels taken from the source and randomly-guessed colors.	Less system-intensive than HQx and xBR. Adequate if it's the best option available (e.g. in Pete's OpenGL2 plugin for PSX emulators).	Edge detection is horrible. Artifacts are common. Posterization is very common. Archaic. The alternatives are much better.
xBR	A modified version of HQx. It detects edges better, which works better for curved lines, or for slopes that are greater than/less than 45 degrees.	Looks great for many 2D games. Edge detection is improved over HQx. This gives textures smoother curves and slopes, as well as fewer artifacts. 3D games look great with it as well.	Posterization is common. There are deposterization filters in some emulators (e.g. PPSSPP) that can aid this, however. The finer details of the textures/sprites might be obscured by bad edge detection. Worse at some things that HQx excels at.
xBRZ	A modified version of xBR, which is very similar except it's better at scaling up smaller features consisting of <10 pixels.	Looks great for many 2D games. Detects small features that get messed up by HQx and xBR. 3D games look great with it as well.	Posterization is common. There are deposterization filters in some emulators (e.g. PPSSPP) that can aid this, however. Worse at some things the other scalers excel at.
MMPX	A texture scaling algorithm. Provides a nearly unfiltered, "Retro Plus" pixel art aesthetic with better handling of rounded and diagonal edges, similar to that found in many indie games.	Has better handling of diagonals and curves than other scalers. Does not alter the art style to look cartoonish or posterized the way HQx and xBR do. Looks great for both 2D and 3D games designed with pixelated graphics in mind.	Looks pixelated, highlighting the low resolution. Textures scaled horizontally and vertically at unequal levels can produce awkward results. Resolution hacks may be able to fix this in some instances.
NNEDI3	A neural network-based "edge-directed" interpolator. It uses a pre-trained model to predict what missing pixels should look like based on existing edges and structures.	Exceptional at preserving sharp edges without the "oil painting" look of xBRZ. Virtually eliminates jagged edges (aliasing) on 2D elements and UI. Considered one of the highest-quality "clean" upscalers available.	Extremely hardware intensive compared to every other filter on this list; requires a capable GPU. Can sometimes introduce small "wobbles" or artifacts in very complex, noisy textures where the AI misidentifies an edge.
ArtCNN	A lightweight Convolutional Neural Network (CNN) designed for real-time upscaling and artifact removal. It uses machine learning to reconstruct sharp edges and smooth gradients.	Produces some of the cleanest results for 2D art and UI elements. Excellent at removing "ringing" and compression artifacts that other scalers might amplify. Provides a much more natural, "hand-drawn" look compared to the "oil painting" effect of xBRZ. Highly optimized; much faster than NNEDI3 while providing similar or better visual clarity.	Requires a GPU that supports modern shader languages (Vulkan/GLSL/HLSL). Can occasionally "over-clean" textures, removing intentional film grain or fine grit in 3D textures. May be too demanding for very low-end integrated graphics or older mobile devices.

Emulator Specific

These are specific options found in emulators like PPSSPP that modify or combine the methods listed above to achieve better results. PPSSPP has a scaling option known as "Hybrid." There's also an option called "Deposterize." Posterization, meaning a sharp contrast in hue from one pixel to another (very common in low-quality gifs) has been a problem plaguing texture scaling algorithms for quite some time. Durante's filter switches between xBR and bilinear/bicubic filtering depending on the texture information. On top of this, the "Deposterize" option tackles posterization edges in compressed textures, allowing for a smooth gradient rather than a sharp transition. Although it's not perfect (a perfect scaler sadly isn't possible with today's computing power) it's still great and it's recommended to use for PPSSPP if you have the specs.

Feature	What it does	Pros	Cons
Hybrid / Hybrid + Bicubic	A scaling method that switches between xBR and bilinear/bicubic filtering depending on the texture information. It attempts to detect which parts of a texture need sharp edge enhancement and which are smooth gradients.	The "best of both worlds": preserves sharp edges where needed while keeping smooth areas (like skies) from looking blocky or "posterized." Generally considered the "Gold Standard" for a balanced look in PPSSPP if the hardware can handle it.	Highly system-intensive. While it aims for a perfect balance, a perfect scaler isn't possible with today's computing power, so some textures may still look slightly inconsistent.
Deposterize	A filter that tackles "posterization" (sharp, ugly jumps in color hue common in compressed textures) by smoothing out the transitions into a natural gradient.	Allows for a smooth gradient rather than a sharp, blocky transition in colors. Greatly reduces the "oil painting" artifacts that often plague other texture scaling algorithms. Highly recommended for use in PPSSPP if you have the specs to support it.	Can occasionally "wash out" textures where sharp color transitions were an intentional part of the art style. Adds extra load to the GPU when combined with high-level scalers.

Images

PSP game with linear filtering
PSP game with nearest neighbor
PSP game with 3xBR texture scaling

N64 game at native internal resolution (using SoftGraphic plugin)
N64 game upscaled with bilinear filtering (using Glide64 plugin)
N64 game upscaled with nearest neighbor (using Glide64 plugin)

SNES game with nearest neighbor
SNES game with linear filtering

SNES game with nearest neighbor
SNES game with HQ4x texture scaling
SNES game with 5xBR texture scaling

Texture filtering hacks

Some emulators features better texture filtering: enhancement option for providing better texture filtering methods comparing the original hardware had. See;

sections.

Framebuffer Scaling & Output Methods

Main article: Scaling