Radeon Image Sharpening
Along with the announcement of the Radeon RX 5700 series at E3, AMD announced some new graphics technologies. One of them, Radeon Image Sharpening (RIS), seems likely to be a response to Nvidia’s DLSS. AMD never says this, even in indirect terms, but instead says the technology is intended to improve the clarity of games softened by post-processing anti-aliasing, or that are played in sub-native resolutions.
Radeon Image Sharpening is fundamentally a post-processing sharpening filter. This is not really all that different from similar filters that are already built into many games and third-party shader packages, like ReShade. The key differences are that RIS is “contrast aware,” and of course that it is built into the graphics driver.
That AMD brings up the former point is curious, because other sources—like the aforementioned ReShade—already have contrast-aware sharpening filters. AMD says its filter is based on its own FidelityFX package’s “Contrast-Adaptive Sharpening” algorithm, and that it is better-tuned as a result. The latter point, driver integration, is important for some folks, because packages like ReShade can cause anti-cheat software to have conniptions.
The primary downside to Radeon Image Sharpening is that it only supports games using the DirectX 9, DirectX 12, and Vulkan APIs. That’s right: no DirectX 11 support, which means that the vast majority of games simply aren’t supported. One could argue that AMD’s choice to focus on DirectX 12 and Vulkan is forward-looking; I think the exclusion of DirectX 11 is downright foolish. (By the way, ReShade doesn’t yet support the Vulkan API.)
Either way, that limitation means that I couldn’t do the head-to-head test against DLSS that I wanted; I simply don’t have any DirectX 12 games that support DLSS. Instead, I benchmarked the Radeon RX 5700 XT in Doom in 2560×1440, in 3840×2160, and in 2560×1440 with Radeon Image Sharpening.
AMD claimed on stage back at E3 that RIS would have negligible performance impact, and that claim seems to hold true. Given how little effect it has on performance, you might expect that it has a similarly-small visual impact. While I think that measuring the actual merit of its effects is muchly a matter of taste, RIS is definitely more obvious than I expected it to be. Specifically in Doom, textures appear more detailed, and HUD elements are sharper and more defined.
I’d show you a screenshot, but RIS’ effects don’t show up in Steam screenshots, and I didn’t have any other way to capture Doom. I then tried to capture the effect in Phantasy Star Online 2 (where it is very obvious), but ran into the same problem. As a post-processing effect that happens in the driver, the only way to actually capture RIS in images is to snag the image from Windows’ compositor itself. Finally, I figured out that I could screenshot RIS in Deus Ex MD and Hitman 2, so peep these captures.
In the case of Deus Ex, Radeon Image Sharpening had a strange interplay with the game’s built in grain filter. This is a lot more noticeable at 2560×1440, where RIS seems to amplify the grain effect to a tremendous level. This makes the game look gritty and detailed, but it can also feel like a bit of a cheap way to achieve same. It had fundamentally the same effect at 4K, but given the surplus of pixels, the extra noise doesn’t feel so intrusive. It serves to highlight lines and make objects stand out from the environment just a bit more, and I like the effect.
The results in Hitman 2 are even more obvious. This time, the effect is more subtle at 2560×1440, yet it’s easy to see if you look carefully. The grass on the left side, the man in the red-and-white striped shirt standing in said grass, the VIP sign in the background, and other areas all exhibit clear signs of the sharpening filter. Frankly, it looks great, although the filter does introduce a bit of additional aliasing. More on that in a moment.
Hitman 2 in 4K doesn’t appear to play nice with the filter. With RIS enabled, it seems as though certain textures either become corrupted or don’t load properly. I didn’t investigate this issue very thoroughly, but I did confirm that it is repeatable. This seems likely to be a game-specific bug with Hitman 2, as I launched several other titles with RIS enabled, and nothing else exhibited this kind of problem.
Too much of a good thing
By the very nature of what it does, Radeon Image Sharpening necessarily increases the amount of aliasing in a scene. Now-near-ubiquitous post-processing anti-aliasing techniques like FXAA and SMAA are essentially smart blur filters, and sharpening things up has the side effect of un-doing some of their work. Still, AMD has done a decent job of programming the algorithm such that it generally avoids edges and focuses on low-contrast areas, adding apparent detail to the interiors of objects and surfaces without over-sharpening the edges. I do wish we could tune the effect for taste, the way you can with ReShade’s very similar LumaSharpen filter.
AMD shies away from specifically comparing low-resolution-with-RIS to native 4K the way Nvidia does with DLSS. It’s a good thing, too; claiming that RIS offers image quality comparable to a 2.25x increase in render resolution would be abject nonsense. The company does seem to think that using RIS on sub-native resolutions is a fair compromise, and I would say that’s really a matter of taste. Whatever you think of RIS, I would say having the option is a net gain for Radeon gamers.