PlayStation 5 Pro arrives complete with a somewhat enigmatic feature - the ability to enhance the image quality of older PS4 software. A toggleable menu option suggests that the new console has the ability to 'improve the resolution of select PS4 games' but there's no explanation of what it actually does. With that in mind, we set out to find out. What exactly does the 'enhance image quality' feature actually do? Is this a game changer for PS5 Pro, or more of an incremental improvement? Let's get down to business by kicking off with a look at a prominent pre-PS4 Pro PS4 title, the original Destiny - and we can confirm that it is indeed making a difference. A close look at fine details reveals a sharper image with the enhanced mode enabled. The most obvious differences understandably come in high contrast areas of the image, such as structures cast against a skybox. The enhanced mode is doing a pretty good job at refining some of the edge detail, but without emphasising edge artifacts, as a naive sharpening filter would typically do. There does appear to be some attempt at reforming edges, eliminating some of the aliasing artifacts we saw before. Edges that used to have obvious sawtooth aliasing artifacts appear less jagged, but simultaneously have sharper edges. However, aliasing patterns can remain, just masked slightly.Our educated guess is that this new technique is a post-process filter that runs after the processing of the PS4 game content - it's a kind of smart upscaler. Everything seen here indicates that it's the same basic game content, running at the same resolution. However, the way the image resolves appears different on PS5 Pro and game content does look noticeably more detailed and slightly more refined. We've got some nice zoomers on this page showing the difference, but seeing the effect in motion is recommended - hence the video.Watch on YouTubeBecause the enhanced mode appears to apply to games as a post-process, all UI elements - like the HUD in Bloodborne, for example - get the same treatment. In some instances, it can bring the old 2D art up to a level of detail and refinement that looks pretty solid at 4K. There is indeed more detail, if slightly smoothed. Batman: Arkham Knight also gets a surprisingly crisp and clean 4K-like HUD, with almost artifact-free upscaling - but in all tests, there are indications that we're looking at an upscaling algorithm for 4K displays, not actual 4K art. It's not going to be a perfect replacement for 4K art, generally speaking. Looking at Metaphor Refantazio's PS4 version on PS5 Pro, the 1080p art benefits with image enhancement, but the actual 4K artwork in the PS5 code gets cleaner linework and more detailed texture. Text, again, is typically well defined with the Pro's upscaling, but not as crisp and artifact-free as actual native 4K text. It's also important to recognize the technique's limitations. The biggest problem with enhanced mode is that it really doesn't do much for temporal aliasing. Shots with movement across a variety of games reveal a similar amount of aliasing between the regular mode and the enhanced equivalent. The character of that aliasing is different, with the enhanced mode taking on a slightly rounded appearance, but the actual level of frame-to-frame breakup is similar. In other words, the enhanced mode essentially inherits the image quality characteristics of the existing game, including its anti-aliasing and it's not necessarily more stable across multiple frames. This means that games like Destiny or Killzone Shadow Fall are still going to appear fairly aliased on the Pro with the enhanced mode. However, games with better AA treatment such as Granblue Fantasy: Relink, look somewhat more detailed without suffering from excessive aliasing. This applies equally to 2D art, as some of the artwork in a game like the first Ace Attorney collection doesn't hold up that well and in some instances, I think the image resolve can actually look a bit messier than before. To see this content please enable targeting cookies. The PS5 Pro claims the enhanced mode is selective - so what games does it apply to? In my testing, it seems like it doesn't apply to PS4 software that outputs above 1080p resolution. Native 4K PS4 Pro titles like Persona 5 Royal and Mantis Burn Racing look identical across both modes, as does 1440p software like Uncharted 4. Overwatch 2, which renders at 1080p internally but has a 4K UI. Likewise for Marvel's Spider-Man, which uses a temporal upscaling technique to hit a 4K resolution. However, some PS4 Pro-enabled software like Rage 2 is visibly changed by the PS5 Pro enhancement process. This game has a 1080p UI and 1080p 3D rendering on PS4 Pro, and it does appear to be enhanced on PS5 Pro. Again, games that are higher res do not seem to get a bump. I don't know if this is a universal rule, however, or if games might be whitelisted or blacklisted based on other criteria, but that has been my experience so far. In general, you should expect to see improvements in PS4 games without a PS4 Pro version, and lower-res PS4 Pro enhanced games, and the improvements should be most obvious in games that present clear, sharp edges without effects like film grain or chromatic aberration. Games with TAA tended to have a more muted visual change relative to games that used post-process AA. And just for the record, the upscaling enhancement appears to be present with the PS5 Pro set to 1440p output or 4K output in the system settings.Outside of image quality, I was interested in the cost of the technique. Very few PS4 games actually run below their frame-rate caps on PS5, but Until Dawn's original release is a notable exception, and a good test-case for the enhanced mode's cost. Curiously, PS5 Pro, running without the enhancement, isn't enough to overcome the game's frame-rate drops on PS5 - but it does run substantially faster than the base console. My guess is that the GPU clocks and GPU resources used to run PS4 software are similar across the two consoles, but that the increased memory speed on Pro is causing a moderate performance improvement here. However, when we introduce the enhance image quality feature, all of a sudden performance drops noticeably on Pro. It's not a gigantic difference, but enhanced image quality drops about 10 percent in performance or slightly more in demanding scenes. It's enough to bring the base PS5 and enhanced PS5 Pro to a virtual performance tie. The vast majority of PS4 software runs at its frame-rate limit with headroom to spare on PS5 consoles, so I don't expect this would be an issue in many titles. This assumes that the performance regression holds true broadly across all games of course, which would require further testing. Regular EnhancedComparison of PS4 content running on PS5 Pro in both regular upscaled and enhanced. Regular EnhancedComparison of PS4 content running on PS5 Pro in both regular upscaled and enhanced. Regular EnhancedComparison of PS4 content running on PS5 Pro in both regular upscaled and enhanced. Regular EnhancedComparison of PS4 content running on PS5 Pro in both regular upscaled and enhanced. Regular EnhancedComparison of PS4 content running on PS5 Pro in both regular upscaled and enhanced. Regular EnhancedComparison of PS4 content running on PS5 Pro in both regular upscaled and enhanced. Regular EnhancedComparison of PS4 content running on PS5 Pro in both regular upscaled and enhanced. Regular EnhancedComparison of PS4 content running on PS5 Pro in both regular upscaled and enhanced. Regular EnhancedComparison of PS4 content running on PS5 Pro in both regular upscaled and enhanced.I did spot one other performance issue with the enhanced mode, which was pointed out to me by CodeMalfunction on the Digital Foundry Supporter Discord. In Just Cause 3, enabling the enhancement causes a major graphics issue, which goes away with the enhanced toggle turned off. I didn't notice any similar issues across testing in dozens of other titles, but there does seem to be some limited potential for graphical bugs. Sony's enhance image quality feature isn't the only game in town when it comes to smart spatial upscaling, however, which is evident if we do some comparisons across PS5 Pro and PC. The most interesting point of comparison is LS1, which is the machine learning-based spatial upscaler available in the Lossless Scaling PC app. In a title like Granblue Fantasy: Relink, which uses TAA, it achieves a sharper, perceptibly more detailed image without the artifacts we'd usually see with sharpening. Comparing LS1 and Sony's enhanced upscaling technique, I'd say Sony's technique slightly edges out LS1 in clarity here, but it's close. Texture detail also looks clearer and sharper without edge ringing - just look at the floorboards here as one example. That inner surface detail appears more pleasing, not just geometric detail. This is an area where LS1 appears substantially better than the Pro. The Pro's enhancement process is comparable to LS1 on text and 2D elements. Both do a substantially better job than 1080p with a naive upscale to 4K, though both exhibit noticeable artifacts and can struggle with different kinds of problems. For instance, Sony's solution has greater difficulty differentiating this line from the background than LS1. There's also Microsoft's AutoSR, which is only available on laptops with the Snapdragon X Elite chip as of this recording. That technology takes a single frame between 700 and 900 vertical lines and upscales it to a higher resolution, delivering higher image detail - and even sometimes better image stability. I haven't gone hands-on with this myself, but I'd say it offers a more comprehensive overhaul than either LS1 or Sony's solution, albeit still inferior to temporal upscaling solutions that use more inputs from the game engine, like DLSS - or indeed Sony's own PSSR upscaler. However, it does incur a one-frame latency penalty.Do you want to know more? Watch Digital Foundry's 100-minute video review.Watch on YouTubeThere are other techniques - like Nvidia's RTX Super Resolution video enhancement - that focus less on game graphics and more on encoded video. RTX Video Super Resolution doesn't really give us as much edge detail as the other solutions, so the actual geometric edges only see a mild increase in definition. That said, the image looks perceptibly cleaner and texture detail is enhanced. FSR 1 is a bit less interesting than the other solutions in my experience, as it has a more uniform impact on the final image. It doesn't upscale text and 2D art quite as effectively and it doesn't do much for texture detail. It works fine enough, but I think the results from the machine learning based upscalers are better - and the potential ceiling is much higher. Based on the visual similarities in results between the 'enhance image quality' toggle and the other machine learning-based techniques, I suspect that the Pro's filter is using machine learning. Its reconstruction of text detail in particular doesn't seem realistically feasible using hand-authored algorithms. That would make sense given the high apparent cost of the technique in Until Dawn on PS5 Pro, as typical spatial upscaling is virtually free on modern GPUs. On a more general level, I think the enhance image quality mode for PS4 software on PS5 Pro is perhaps a preview of the future. Console backwards compatibility efforts have struggled against the constraints of older hardware, unlike the PC where games can usually scale in fidelity. It's not possible to expose the full capabilities of the PS5 Pro's GPU to a PS4 title, and increasing resolution for older games requires case-by-case effort that can't be applied broadly across all titles. A post-process filter that could substantially improve image quality in these older games is a scalable concept and doesn't actually require that older game code to take advantage of new hardware capabilities. A more sophisticated filter in the future could greatly improve image quality while still allowing for a high level of software compatibility. However, Sony's image quality enhancement on PS5 Pro offers a more moderate bump to image quality in PS4 software. It improves image detail and clarity somewhat, but temporal consistency is about the same as before. An enhancement is needed most with early PS4 games that lack PS4 Pro support, as these titles often had big issues with shimmer and flickering, so the lack of an improvement there is unfortunate. It's also not quite at the bleeding edge of smart spatial upscalers. In particular, Microsoft's Auto SR boasts a greater image transformation, albeit with a more limited range of compatible source content. Perhaps in time Sony can come up with something similar. Still, the PS5 Pro's image quality enhancement feature is a nice little boost to make PS4 software more palatable on high-res displays. The PS5 Pro offers far greater boosts to actual PS5 games, but it's nice to see some attention put towards older software.