Has Microsoft fixed the Xbox One scaler?

Digital Foundry on how the new system software improves sub-1080p image quality.

Killer Instinct - a 720p native Xbox One exclusive suffered worst from the Xbox One's sub-par hardware scaler. Has it improved with the new system update released last weekend?

Microsoft hasn't made things easy for itself. For a console with so many sub-1080p games, the quality of its internal hardware scaler has been deeply unsatisfactory up to now, resulting in poorer-than-expected image quality in a lot of key exclusives and multi-platform titles. The good news is that this weekend's Xbox One system update, which followed hot on the heels of the Titanfall beta, has seen Microsoft take positive steps in resolving the issue.

First things first, though: what went wrong with the pre-patch scaler? Well, most notably, image quality was compromised by a poorly judged sharpening filter that actually emphasised jagged edges, while a distinct gamma shift was also visible on several games, resulting in unnaturally high contrasts that didn't exactly complement the artificially enhanced edges and upscaling artefacts. Ultimately, rather than helping titles such as Call of Duty: Ghosts and Assassin's Creed 4 better stand up to PS4 equivalents running at native 1080p, the scaler made them look significantly worse.

Up until the new firmware shipped over the weekend, the only way to circumvent the sharpening filter on native 720p titles was by manually switching the console to match the game resolution, thus letting your TV or monitor take care of the scaling. However, this constant swapping between display modes was obviously a hassle and most people would never bother. It didn't solve the problem anyway: while games such as Dead Rising 3, Killer Instinct and Call of Duty appeared smoother and more natural this way rather than using the scaler, forcing 720p output didn't seem to entirely disable the unwanted filter. A close look at edges on a pixel level showed that the sharpening effect (halos around objects) was still present, just operating with a significantly lower intensity. Furthermore, the technique simply didn't work on games that rendered in resolutions higher than 720p but below 1080p, such as Assassin's Creed (1600x900) and indeed the precious Titanfall beta (1408x792).

So, how much of a difference does the new Xbox One firmware make? Is the sharpening effect gone, and what changes if any have been made to the scaling algorithm and the existing gamma set-up? In the run-up to the Xbox One launch, Microsoft promised us a quality upscaling solution, so we couldn't help wonder whether this update would finally deliver...

Launch Scaler Updated Scaler

After the update it is clear that the unsightly halos caused by the sharpening filter are completely gone. A close look at the pixel structure reveals that the only artefacts on-screen are the ones created by resizing the image from 900p to 1080p. As such the edges of foliage and finely detailed objects now appear smoother and more defined than before.

Launch Scaler Updated Scaler

After the update it is clear that the unsightly halos caused by the sharpening filter are completely gone. A close look at the pixel structure reveals that the only artefacts on-screen are the ones created by resizing the image from 900p to 1080p. As such the edges of foliage and finely detailed objects now appear smoother and more defined than before.

Launch Scaler Updated Scaler 720p with Simulated HDTV Upscale

Our previous method of manually forcing 720p output on the Xbox One and letting our display do the scaling improved things massively, even before the update, dramatically reducing the sharpening effect around edges. However, the update disables these edge artefacts more clearly, negating the need to use our HDTV's superior scaling capabilities.

Launch Scaler Updated Scaler

The removal of the sharpening filter takes away some of the rough, overly processed look from Call of Duty: Ghosts. However, the poor-quality scaling used by the game itself means that jaggies and other artefacts are still more visible than we'd like - something that this update is powerless to improve.

First up, the 1600x900 Assassin's Creed 4 is definitely improved - the sharpening effect has gone, removing the halos around detail. What we have now is an image very similar to the launch version on PS4 prior to its 1080p patch. The removal of the sharpening filter is also evident in titles rendering natively in 720p, resulting in a similar boost in overall picture quality. As with AC4, there's less harshness to fine detail across the games previously affected by the destructive sharpening effect. The improvement really stands out in Killer Instinct, with characters and scenery now completely free from the processed look that previously characterised the artwork.

With that said, not every game benefits to the same extent. In particular, the poor-quality scaling used in Call of Duty: Ghosts still gives the visuals a muddy appearance compared to the 1080p PS4 game. Indeed, upon reviewing our video captures it becomes clear that while the sharpening effect is gone, the quality of the actual scaling performed by the Xbox One hardware seems unchanged. The same core algorithms still seem to be at work following the firmware update, it's just the sharpening filter that has gone.

The update also fails to tackle the contrast/gamma boosting that is visible in these games, so we still see an unnatural bias to both light and dark areas, with Killer Instinct and Call of Duty: Ghosts noticeably affected. It appears that the sharpening filter and gamma boosting properties are separate entities entirely, and in this case Microsoft has simply decided to keep its preferred high-contrast output intact - at least for now.

Launch Scaler Updated Scaler

Scaling quality remains unchanged before and after the update, so there are still noticeable artefacts around edges and sub-pixel elements in Titanfall, although without the sharpening filter these compromises stand out less obviously than they used to do.

Launch Scaler Updated Scaler

Scaling quality remains unchanged before and after the update, so there are still noticeable artefacts around edges and sub-pixel elements in Titanfall, although without the sharpening filter these compromises stand out less obviously than they used to do.

Launch Scaler Updated Scaler

One of the native 720p titles to benefit most from the recent update, Killer Instinct now features a much cleaner look than with the filter previously applied. Fine details are better resolved across the artwork, and geometry edges appear smoother.

Launch Scaler Updated Scaler

While the update does indeed remove the unsightly halos from sub-1080p games in the Xbox One, the boosted gamma set-up remains in effect. This leads to crushing of details rendered in dark areas, while bright highlights still appear rather overblown.

The assets on this page should give you a sense of what's changed and what hasn't. You can see that the strong halos that previously appeared around various edges in games like Assassin's Creed 4 and Titanfall are gone, allowing detail in the artwork to come across without giving textures a rough and grainy appearance or presenting quite so many prominent jagged edges. AC4 probably demonstrates this best, with the 900p resolution showing up fewer artefacts than the 1408x792 Titanfall beta, where the unusual framebuffer size doesn't seem to scale quite so comfortably to 1080p.

It's interesting to note that the majority of native 1080p titles - including Need for Speed: Rivals, Lego Marvel Super Heroes and Tomb Raider - do not have gamma issues at all. Developer contacts tell us that the phenomenon is linked to the use of the Xbox One scaler in combination with the utilisation of multiple display planes (allowing native and sub-native elements to blend in the final framebuffer). This is backed up by our experience with Battlefield 4. The pre-final code utilised the Xbox One hardware scaler and featured an unnatural gamma shift, while the release version saw the implementation of a software scaler created by DICE itself that resolved the colour balance issue in addition to removing the sharpening effect.

Overall, then, the new Xbox One firmware update has changed things for the better, but you shouldn't expect an enormous boost in the quality of the final image. The unsightly sharpening filter has been consigned to the scrapheap of technological history, removing a 'feature' that really shouldn't have been there in the first place, but while the resulting improvement to picture quality is considerable and mostly positive, colour balance is still an issue, and the quality of the scaling itself is unchanged.

There is certainly room for improvement, then, but for now, with the sharpening filter completely gone, results will be good enough for most gamers. While improved scaling can rarely match a palpable boost in raw resolution, overall picture quality is a significant step up from what we were dealing with before, which is a definite win for owners of Microsoft's system.

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