What was once a rumour is now confirmed. At least some cross-platform games will run at a higher resolution on the Sony PlayStation 4 than on Microsoft's Xbox One.

But why is this happening and should it influence your decision over which of the next-gen game boxes to buy?

The confirmation comes in the form Call of Duty: Ghosts. Developer Infinity Ward says it will run at 1080p on the PS4 but only 720p on the Xbox One. For clarity, that's 1,920 by 1,080 pixels versus 1,280 by 720 pixels.

Put another way, that's two million pixels on the PS4, just one million on the Xbox One. Quite literally, the PS4 will offer double the graphical detail.

Does the difference matter?

The first question is whether this actually matters. The answer is yes, it matters. Admittedly, some people are more sensitive to graphical fidelity than others. But double the detail is a substantial difference by any metric.

That said, when there is a difference with a given game, it may not always be 720p vs 1080p. Hold that thought.

What's important to understand up front is that 1080p on an HDTV doesn't outstrip the acuity of the human eye at normal viewing distances. This is what Apple means when it talks of 'retina' displays. It means from normal viewing distances, the human eye doesn't resolve individual pixels.

But if you have decent vision, a 1080p HDTV isn't a 'retina' display. Which is why 4K displays looks miles better than 1080p displays. And in turn 720p doesn't look as sharp as 1080p.

BF4
Games running at native 1080p resolution will look better

The importance of native resolution

There's a further angle to this resolution problem. It's not just a matter of doubling the pixel count. It's the clarity of each pixel, too. The issue here involves native panel resolutions. Flat panels including LCD and OLED screens have an absolutely fixed number of pixels, unlike old school CRT screens.

That means there's just a single ideal resolution the panel can run at, only one setting at which images are shown pixel for pixel. Before the pedants drop a bomb in the comments below, pixel doubling could be argued to be an exception. But pixel doubling involves factor-of-four jumps in resolution.

'...there's no way round the problems you incur when attempting to spread one pixel over one and a bit pixels. You will always lose some sharpness and clarity'

Put another way, 720p to 1080p is not pixel doubling, so it's irrelevant to the PS4 vs Xbox One debate.

Anyway, most big HDTVs are now 1080p, not 720p. So not only do you lose pixels when dropping down from 1080p to 720p when gaming. You also lose clarity of individual pixels, since at 720p you have to use an algorithm to interpolate larger pixels over a non factorial number of smaller pixels. It's basically a horrible kludge that results in soft, slightly blurry images.

This applies to an extent even if you do the interpolation in the game engine and actually output 1080p to the screen. There's been talk, for instance, of the Xbox One rendering Battlefield 4 at 900p internally and then upscaling the output. But there's no way round the problems you incur when attempting to spread one pixel over one and a bit pixels. You will always lose some sharpness and clarity.

Why is this happening?

So, we now know the difference matters. The next question is why is this happening? Actually, that's easy to answer. It's because the PS4 is more powerful in graphics terms. And that means the PS4 can render higher detail graphics while maintaining smooth, playable frame rates.

Both consoles are based on very similar basic architectures, with CPU and graphics provided by chip specialist AMD. In fact, the two share pretty much identical eight-core CPUs. So we don't have to worry about that.

Where the big differences come in are graphics and memory subsystems. PS4 and Xbox One actually use identical graphics architectures, known as AMD's GCN technology. But here's the thing. The Xbox One has 768 GCN graphics cores. The PS4 has 1,152. The two consoles run at similar clockspeeds, so right from the get go, the PS4 has 50 per cent more raw shader power.