Tech Blog
March 18, 2026
Bringing stunning visuals to UE mobile games with Arm Accuracy Super Resolution
Arm is at the heart of mobile gaming. With 99% of smartphones running on Arm, we’re an essential compute platform for mobile game developers worldwide to build, optimize, and deploy high-performing, efficient, and engaging games.
Hello Unreal Engine community. I’m Julie Gaskin, Staff Developer Evangelist, from the ARM Ecosystem Team. Visual quality is now a frontline priority for mobile game developers. With each generation, mobile hardware grows more capable, narrowing the gap between smartphones and traditional gaming platforms. GPU power is rising, and features once reserved for PC and consoles, like complex lighting and high-fidelity effects, are becoming increasingly common in mobile titles.
But even with these advances, mobile devices still face tight limits. They’re battery-powered, prone to overheating, and render to high-resolution displays with extremely dense pixels. That makes every pixel and every optimization count.
Modern mobile games are pushing these limits with complex lighting, post-processing effects, dynamic worlds, and even early explorations of ray tracing. However, rendering to densely packed screens at high frame rates takes a toll. It draws significant power, taxes the GPU, and drains the battery quickly—especially when aiming for the kind of visual polish players now expect.
But even with these advances, mobile devices still face tight limits. They’re battery-powered, prone to overheating, and render to high-resolution displays with extremely dense pixels. That makes every pixel and every optimization count.
Modern mobile games are pushing these limits with complex lighting, post-processing effects, dynamic worlds, and even early explorations of ray tracing. However, rendering to densely packed screens at high frame rates takes a toll. It draws significant power, taxes the GPU, and drains the battery quickly—especially when aiming for the kind of visual polish players now expect.
Upscaling on mobile
Enter upscaling. By rendering at a lower resolution and then intelligently reconstructing the image, you can reduce GPU load while maintaining visual quality.
On PC and console, there are multiple advanced upscaling methods—spatial, spatial-temporal, and machine learning-based solutions—which deliver impressive results. But these techniques often don’t translate well to mobile. They’re either:
- Too computationally heavy
- Too power-hungry
- Or simply not optimized for the constraints of a smartphone
Arm Accuracy Super Resolution (Arm ASR)
Designed for mobile, Arm Accuracy Super Resolution (Arm ASR) is a shader-based, temporal upscaler that delivers high-quality image reconstruction with a strong focus on efficiency. This means developers can significantly reduce GPU workload on high-end content, without loss in visual fidelity.
Arm ASR builds on the foundation of AMD’s FidelityFX™ Super Resolution 2 (FSR 2); an open-source temporal upscaling solution that has proven itself in PC and console gaming. We extended and optimized FSR2 to create a version tailored specifically for the unique demands of mobile. The result is Arm ASR, a super resolution solution that brings the power of FSR2 to resource-constrained environments.
Understanding GPU and CPU bottlenecks
To get the most out of Arm ASR, it’s important to understand when and where it provides the biggest benefits. Mobile GPUs process graphics workloads in two main stages: geometry processing and pixel (fragment) processing:
- Geometry processing handles the drawing of objects, transforming and culling vertices.
- Pixel processing, also known as fragment shading, colors each pixel on screen, applying lighting, textures, and other effects. It also performs depth and stencil testing to discard hidden fragments.
Arm ASR is best-suited for fragment-bound content. That’s where the GPU is heavily loaded during the pixel shading stage, either due to a high number of fragments on screen or complex fragment shaders. In these scenarios, ASR helps by reducing the number of pixels that need to be shaded, improving performance and power efficiency.
However, in vertex-bound scenes, where geometry is the main bottleneck, Arm ASR may have limited impact. For those cases, performance improvements will come more from content optimizations such as mesh simplification or culling techniques.
Similarly, if your game is CPU-bound, such as when physics, animation, or draw call submission is overloading the processor, ASR won’t help much either. Reducing GPU load won’t improve performance if the CPU is already the bottleneck.
To identify whether your game is CPU-, vertex- or fragment-bound, you can profile your game on real Android devices using tools like Arm Performance Studio. This helps ensure you apply the right optimization strategy for your rendering bottleneck.
How Fortnite uses Arm ASR to push mobile gaming further
When you’re shipping a game as visually ambitious and performance-demanding as Fortnite, you’re always looking for ways to stretch every bit of power from mobile hardware.
Mobile devices are under constant pressure from both CPU and GPU workloads, especially when aiming for consistent 60Hz gameplay. Arm ASR is a way to reduce GPU pressure while preserving (and in some cases improving) the visual quality we deliver to players.
But what really makes Arm ASR powerful is this: it allows the team to re-enable features previously disabled on mobile just to stay under thermal and performance limits. Features like ambient occlusion, additional shadow cascades, and post-processing enhancements are now viable again, even during extended play sessions.
Mobile devices are under constant pressure from both CPU and GPU workloads, especially when aiming for consistent 60Hz gameplay. Arm ASR is a way to reduce GPU pressure while preserving (and in some cases improving) the visual quality we deliver to players.
But what really makes Arm ASR powerful is this: it allows the team to re-enable features previously disabled on mobile just to stay under thermal and performance limits. Features like ambient occlusion, additional shadow cascades, and post-processing enhancements are now viable again, even during extended play sessions.
Smooth integration with real impact
Arm ASR was nearly drop-in ready when the Fortnite team began integrating it. They had to make a few renderer-side adjustments, particularly around how their mobile pipeline handled scene inputs (a change that was upstreamed into Unreal Engine). One of the earliest challenges was ghosting, especially in fast-moving scenes or where transparency was involved, such as foliage, particle effects, or weapon glints.
To resolve that, the team enabled the reactive mask, a feature that dynamically identifies pixels where temporal artifacts are likely. They integrated this capability directly into the mobile renderer API, so the mask updates in real time based on scene changes. The result? Ghosting is minimized, and image stability is greatly improved. The engine-side changes made to support this are now available in the latest version of Unreal Engine.
Here are the code-level integration highlights:
- Modified PrePostProcess RHI commands
- Added mobile renderer inputs
- Conditional use of MobileSceneTextures or DeferredSceneTextures, depending on availability
Designed to protect performance over time
Originally, Fortnite’s primary goal with Arm ASR was thermal and power optimization, which is especially important on high-end devices targeting 60Hz. With Arm ASR enabled, there were immediate reductions in GPU time, which translated directly to lower skin temperatures, less thermal throttling, and longer sustained play.
But this isn’t just about saving power—it’s about protecting performance across long sessions. Fewer thermal spikes mean more consistent frame rates, smoother gameplay, and happier players.
Optimizing for vertex-limited scenes
That freed-up GPU time unlocked new possibilities for the content team. In Fortnite, it’s often vertex-limited, especially in large, open-world areas. To free up more breathing room, the Fortnite development team began optimizing geometry throughput, most notably through a new, experimental low-vertex landscape system.
With Arm ASR and geometry optimizations working in tandem, they’ve gained enough headroom to re-enable advanced visual features without compromising frame rate:
- Higher-quality shadows with more cascades
- Ambient occlusion
- Enhanced post-processing effects
Looking ahead: Desktop-class features on mobile
Now that Arm ASR is fully integrated, Fortnite is looking ahead to even bigger visual gains:
- Unlocking Shader Model 5 for mobile
- Enabling desktop-class features
- Bridging the visual gap across platforms without sacrificing performance
Scalable by design: Presets for every device tier
Not all mobile devices are created equal, and neither are the trade-offs that game developers face. Arm ASR comes with a set of flexible quality presets, enabling you to tailor the upscaling experience to the capabilities of your target hardware.
Arm ASR includes three built-in quality presets, giving you control over performance and visual trade-offs:
- Quality Mode - For titles where visual impact is king, this preset enhances image quality to the highest level. It’s ideal when you’re targeting premium devices and want to push fidelity as far as mobile allows. Naturally, this comes with a higher performance cost.
- Balanced Mode - This is the sweet spot, and the default Arm recommends. Balanced mode delivers an optimal mix of image quality and performance, making it well-suited for a wide range of mid-to-high-end devices. If you’re looking to hit consistent frame rates without sacrificing too much visual detail, this is your go-to.
- Performance Mode - When efficiency is critical, Performance mode shifts the emphasis to speed. It reduces the image quality slightly to maximize frame rate and responsiveness.
Arm ASR is best suited for devices from 2022 onward. Older phones may lack the GPU efficiency needed for temporal upscaling. For those, a fallback spatial upscaler is a better choice.
One solution, every platform: Arm ASR is fully agnostic
Arm ASR is platform-agnostic and vendor-neutral. It runs on any GPU and supports all major graphics APIs, including Vulkan, OpenGL ES, and DirectX 11 and 12.
Because it’s fully shader-based, ASR integrates smoothly into any pipeline, whether you’re targeting Android, iOS, or considering cross-platform deployment.