Tech's New Most Meaningless Spec: PPI

HTC's new Droid DNA smartphone has plenty of qualities that make it intriguing. It has a quad-core Snapdragon chipset. It crams a 5-inch display in a body nearly the size of a One X or Galaxy S III. Its Super LCD 3 technology trumps the Super LCD 2 that made the HTC 8x display so lovely. By all accounts it's a wonderful device. But one thing HTC takes particular pride in is the 1920x1080 display, good for a pixel density of 440 pixels per inch, the highest ever in any handheld consumer device. This should make tech nerds lose their shit, right? Not quite. Welcome to your new favourite meaningless stat: ppi.

The problem with most specs is that beyond a certain point, they fail to be useful. You might remember that when digital cameras first appeared, they left plenty of room for improvement. Part of that improvement involved adding megapixels to the sensor, since getting more detail from the sensor typically involved increasing the dimensions of the image itself. But at some point in the mid-2000s, an increase in megapixels no longer meant it was a surefire sign of improvement. My 5MP camera started taking better pictures than your 10MP shooter. Beyond a certain point, unless you're planning on blowing up your picture to the size of a warehouse wall, megapixels just don't matter.

This same line of thinking manifested itself when contrast ratio became a spec for Plasma and LCD displays (OMG ONE ZILLION TO ONE CONTRAST RATIO) -- can't see it, doesn't matter -- and is now resurfacing as companies enter the pixel density arms race. Increases in pixel density are going from impressive technical feats to masturbatory experiments for the sake of marketing strategy.

So what do we make of HTC managing to pack a 1920x1080 display in a 5-inch screen? When it comes to tangible user benefits, not much. According to those who toil away in research labs, the human eye can not discern granular detail when it is higher than 300 PPI. Hence Apple's 326 PPI display in the iPhone 4 back in 2010. Yes, some -- notably Dr Raymond Soneira of DisplayMate -- have argued that no display will be perfectly "retina" until it has a density of 477 PPI. But others, like University of Utah professor Bryan Jones, dispute the basis of Soneira's reasoning, arguing that from a foot away, displays will actually appear retina when greater than 287 PPI. But even Soneira acknowledged that the retina effect kicks in when a 300 PPI display is held 18 inches away. You know. Where you hold your phone.

Does increased smartphone resolution help for watching high-def movies? Not really. To really reap the benefit of 1080p video, you need no smaller than a 40-inch display (and ideally one above 50-inches) to notice anything awesome while sitting at a comfortable distance. In fact, to theoretically reap any benefits of 1080p video on your phone, you'd need to be holding it 6-8 inches from your face. No one holds their phone 6-8 inches from their face.

Sure, you can get yourself some added digital real estate with a 1080p smartphone display, but you run the risk of making everything too small to easily view. In fact, the only tangible benefit of a 1080p is that a phone's chipset doesn't then have to waste horsepower scaling down the resolution of high-def content. That's a minor reward, though, one offset by all that pixel-pushing gobbling up hardware resources and battery life.

That's not to say that the Droid DNA has a bad screen by any means. In fact, our own Brent Rose thinks its the best smartphone screen he's ever seen, citing its rich colours, and sharp text. But that more to do with HTC's Super LCD 3 technology and its rendering engines as it does raw pixel density, in the same way that a camera's ISO performance matters far more than its megapixelage.

Does this mean that the display wars are over, and everyone should give up on trying to make better screens? Of course not. There are plenty of ways to make a better-looking display. But we've reached the point in the pixel density wars where higher figures have stopped automatically equating to improved performance for users. Any grandstanding about pixel density, from here on out, now is mostly just marketing fluff.



    I think the next step for mobile displays is efficiency. As the owner of a One X I can safely say that the screen is both the best and worst part of this phone.

    As both battery and display technologies advance, I think the next milestone will be a beautiful 4.7" screen that runs for close to a week like my old Sony Ericsson did..

      I would like the next step to be less reflectance. I would love to use my devices under the sun without feeling it is a mirror.

        I don't know if you've seen the Nokia pureblack displays, but they are truly something to behold in direct sunlight.

      If you used your phone as often as your old Sony Ericsson and for the same reasons (calls/texts only) it probably would.

        That's a fair point, Blake. But I hate the feeling that I can't read Giz for half an hour on the bus in the morning if I want my phone to last me until I get home. I have to carry a portable battery in my bag if I plan to be out of the house for more than 12 hours.

    You shouldn't play both sides of the same coin. You praise one company's product because it has a "retina" display and now you bag another company's product because its screen is better still.

      They aren't.

      They praise all companies who reach a required standard. They aren't saying it isn't a technical achievement. They are saying the the ppi in this phone is completely pointless, and due to the range of android devices it introduces additional scaling issues.

      And do not act like this is a subtle go apple article. They were plenty critical a out the lack of pixel density in the iPad mini.

        What mythical standard are you referring to? A company's product technically surpasses another's and that somehow becomes a negative achievement - ridiculous.

          You're either a cheerleader for a particular company or you're just plain thick. The point of the article is simple: ppi numbers only offer a noticeably better picture up to a certain point unless you have the phone glued to your eyeballs (and even then there'd be limits).

          So yes, by that standard it is perfectly reasonable and rational to state that - as you put it: "A company's product technically surpasses another's and that somehow becomes a negative achievement". And it's BLINDINGLY OBVIOUS why; if your technical achievement offers no noticeable benefit to a human being (ya know, the ones using it), but blows processing and battery power whilst delivering this pointless "achievement", then it pretty clearly is a "negative".

          A dose of pragmatism wouldn't hurt here. The author is right: at a certain point specs of all ranges become nothing more than a glorified pissing contest.

    "the retina effect kicks in when a 300 PPI display is held 18 inches away. You know. Where you hold your phone."
    "No one holds their phone 6-8 inches from their face."

    Most users actually hold their smartphones around 12"/30cm from their face. Depending on what they are looking at, 6-8 inches isn't that far-fetched.

    Unless you are using the new iRuler Mini to take measurements, everyone knows the units on that aren't accurate.

    Decent article buddy. I really liked the fact that you backed it up with some references to articles and all that.

    "Beyond a certain point, unless you’re planning on blowing up your picture to the size of a warehouse wall, megapixels just don’t matter."

    While this is true, as we saw with Canon for example who ended up actually lowering the MP count on one of their product series, it doesn't make MP (or PPI) "meaningless". It just means there are limits to efficiency and so on.

    When I'm using a phone, like reading an SMS I'm not analysing the pixels. If it doesn't work for something then it matters - say web browsing is easier to see when zoomed out. But otherwise call it a null point.

    If Apple does it, the whole industry goes oooh and aaah. When Apple first brought out retina, Gizmodo was heaping praises over praises. So now others are beating the specs, you call it pointless.

    I am yet to see an article in Giz that picks out a spec in Apple products and call it pointless.

      The reason they see it as pointless, is because Apple marketed Retina as the full stop of displays. Steve shouted to the world that it's the limit and implied going higher is pointless. He made people believe this so other companies would be hard pressed to one-up Apple on displays and consumers wouldn't believe another company could, and wouldn't care even if they did beat it because Steve knows how eyes work. But you can get better, a higher res WILL have more information for your brain, and it should get better. Retina is not the full stop, it's just a comma before the 'however'.

        It's not about what apple says, it's about there needing to be a line somewhere. A full stop as you call it. It's obvious that 300 ppi is a better screen than 72ppi. It's not obvious that 400ppi is better than 300. At what point does it become a meaningless number that no longer differentiates the product? I actually love the fact that it is a percieved differentiator, because it is pushing the tech forward in ways that only a multi-billion dollar market can and that's useful in other areas, but I do question its utility for a phone screen.

          Imagine a world, where every display on earth is the exact same (PPI), it's highly efficient and low power, extremely high PPI, brilliant colors and brightness, extremely reliable and because it's incredibly cheap to manufacture, there's no reason to not use it in every single device, including alarm clocks or your oven timer. Kind of a universal display that isn't worse or better then any other because they're all perfect. It could happen if we let it, but if we let the big tech companies have their way, we're stuck with over priced, half-arsed fragmented displays.... Why can't this world of universal components exist? Why is that a problem for the future and not something we can't try and achieve now?

          Last edited 14/11/12 1:11 pm

            Well, there is a world where we perceive all of that... It's called the world outside your screen.

            Honestly, I think the PPI comparison is useful, to a point. There *are* instances where you'll use a phone right up close, so there's still room to grow yet.

          Actually that is not true at all. 72dpi is fine for a TV screen because you sit a long way from it. Packing in 300dpi probably wouldn't make a noticeable difference from normal viewing distances.

    "To really reap the benefit of 1080p video, you need no smaller than a 40-inch display (and ideally one above 50-inches)"

    Absolute rubbish.

    I can't wait to have a higher def screen than 1080p, I would definitely notice it on my 46", and to be honest as much as I'd love a big TV, I don't think I could deal with the pixelation on a massive TV at 1080p, not matter how much the "you can't see it" brigade harp on about it.

    As for a phone though, I'm still pretty excited to be getting a 720p phone soon, I'm sure 1080 looks a little nicer, but I doubt i'll be seeing pixels on 720 except for possibly using the phone in bed.

    Retina is just that - A high PPI display. PPI isn't new either, it's an old spec but back in the day it didn't mean much because as monitor sizes changed, the resolution was the important factor. Now with screens in almost everything at different sizes and resolutions, PPI is much better way of determining display clarity than resolution.

      You said it better!

      PPI is for screens as DPI is for printers: laser printers default to 300 DPI because that's the point at which 99.99% of people can't see jaggies in text. Once you get past that, other factors become more important.

    I think its about time the author step our of the reality distortion field and into the real world

      While the absolute thresholds might be significantly larger, it gets to the stage of diminishing returns. I'd much rather see phone companies put more effort into optimizing battery life or colours rather than bumping the PPI up any more. I love 300 PPI+ screens, but like the author says, PPI isn't everything.

      Absolutely agree. I don't want to feel like im looking at a screen. Though i think for this sort of ppi interaction to occur we are gonna have to get truly resolution independent in development and move to vector based computing. it'll give the moore's law people something to work for too :P

    agreed ! typical gizmodo this is such a biased article, gizmodo tends to love all things apple

    PPI when relative to screen size sure. I think Apple hit the optimal mark when it comes to phones. But then thats also when reference to screen technology. Example being pentile on an s3. It is clear and crisp for most everything. But at night for whay ever reason when u r reading in bed and u have red or green text on a dark screen u can easily see the pixels because of sub oixel arrangement. I agree that soon enough it will be a irrelevant when most screen tech reaches optimal for screen distance.

    "No one holds their phone 6-8 inches from their face"- obv never had to stand in peak hour on a train.

      Probably because he isn't poor enough to have to do that.

    We reached the point of marketing fluff once people started using the word "retina" in relation to screens.

    i really was considering the nokia lumia 920 until i learnt about this phone, but when will we get to see it over here in Australia? I hear rumour of a US Nov 21st release date? (unconfirmed)

    I think the 800x480 ClearBlack AMOLED display on my Lumia800 is still the best looking display I've seen on any phone, and it is a dreaded pentile display. I think it is mostly in your mind and in blind tests I reckon most would have serious problems picking the "retina" level display from a really good non-retina. Yes, it is a factor but it is by no means the most important.

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