HTC's Ultrapixels - Bucking The Trend

With the One, HTC has taken an incredibly daring direction for camera. Last year’s One X, One S, and rest of the One series included an ambitious F/2.0 system, discrete ISP, and set an impressive imaging baseline. A full year later, few of the major players are shipping an F/2.0 system (though Nokia will ship an F/1.9 system later this year and has the F/2.0 Lumia 920), but with the One, camera is even more of a serious emphasis. In fact, the camera in the One is surprisingly perhaps the most interesting and ambitious feature of all, outclassing even the unibody aluminum construction. The short list of features on the HTC One camera that make it unique are an F/2.0 system with larger than the norm 2.0 micron pixels, optical image stabilization (OIS), and a new revision of imagechip.

For years now, smartphone manufacturers have been moving to smaller and smaller pixels to increase the resolution of their cameras. It’s the megapixel race all over again, but in the smartphone platform. I gave a presentation at an industry event and laid out the general trends that I’ve seen smartphones taking for the past years. In general, there has been a progression from 1.75 micron pixels, to 1.4 micron pixels, now to 1.1 micron pixels on smartphone CMOS imagers. The result has been a steady increase in megapixels for the same 1/3” or 1/3.2” sensor size common for smartphones, from 5 MP to 8 MP to 13 MP, respectively, for those pixel sizes at the same optical format size. Conversely, OEMs can also deliver the same number of megapixels on a smaller and smaller sensor each generation, for example 8 MP at 1.4 microns on a 1/3.2“ sensor, or 8 MP at 1.1 microns on a 1/4” sensor. At the same time, smaller sensor means smaller z height required for the optics, which often is the thickest part of a design. There’s this constant battle between, you guessed it, industrial design and the camera system that goes in a smartphone.

Though improvements to quantum efficiency (think sensitivity, whether every photon is converted to an electron) at each successively smaller pixel size have mitigated some of the downsides from having smaller effective integration area for a pixel each time, there are still downsides to going smaller. Smaller pixels require an even better optical system to resolve that resolution, and already imaging onto pixels at 1.4 microns is really just oversampling. With the bayer color filter on top, you can make an argument that it isn’t really oversampling given the 2x2 nature of the array, but the reality is that we can’t image a spot onto a single 1.1µm pixel even with diffraction limited optics. Other downsides to smaller pixels are again a loss of sensitivity, partially from having a smaller integration area, partially from other things like the smaller active region for the sensor and a change in drive voltage. The other problem is loss of dynamic range before saturation occurs - already smartphones are operating with a dynamic range of around 5,000 photoelectrons. This means a very narrow range of brightnesses that can be represented inside the normal 10 bits of data shipped back from a given pixel at a given exposure.

The end result to this game is a ton of tradeoffs. In the case of the very high 13 MP cameras that are emerging today, we’re talking about an image that might not even be sharp outside in bright daylight if the optical system can’t resolve a high enough spatial frequency for the sensor, potentially very compressed dynamic range, and less and less sensitivity indoors in dim or low lighting. This year at the high end the trend is predominately 1.1 micron pixels, and basically any 13 MP camera you see in a smartphone is going to come with them. Likewise there’s a huge push for HDR this year in just about every mode (photos, videos, and panorama), and the reason is pretty much entirely to mitigate the fact that smartphone platform cameras just don’t have a lot of it before they saturate.

With the One camera, HTC has gone the other way entirely, instead moving up the scale to bigger 2.0 micron pixels while others move down to 1.1, while last year everyone primarily shipped at 1.4 microns. They’ve branded this the ‘UltraPixel sensor’, but really the important thing to think about is that the pixels are 4 square microns (2.0 x 2.0 micron) compared to the flavor-du-jour 1.21 square microns (1.1 x 1.1 micron) and thus have just over 3x the area. The result is, like anything else, a tradeoff but in the other direction - improved low light sensitivity and dynamic range at the expense of spatial resolution. At 1/3" sensor size, use of 2.0 micron pixels translates to 4.0 MP of resolution.

Smartphone Camera Comparison - 2013
  HTC One Samsung Galaxy S 2 Samsung Galaxy S 3 Samsung Galaxy S 4
Front Camera 2.1MP 2MP 1.9MP 2MP
Front Camera - CMOS OV2722
(1.4µm, 1/5.8")
- S5K6A3
(1.75µm, 1/6")
S5K6B2
(1.34µm, 1/6")
Front Camera - Focal Length ~1.59mm 2.73mm 2.7mm 1.85mm
Front Camera - Max Aperture F/2.0 F/2.8 F/2.8 F/2.4
Rear Camera 4MP 8MP 8MP 13MP
Rear Camera - CMOS ST VD6869
(2.0 µm, 1/3")
S5K3H2YX
(1.4µm 1/3.2")
Sony/Samsung
(1.4µm, ~1/3")
IMX135
(1.12µm, 1/3.")
Rear Camera - Focal Length 3.82mm
(28mm eff)
3.97mm 3.7mm 4.2mm
(31 mm eff)
Rear Camera - Max Aperture F/2.0 F/2.65 F/2.6 F/2.2

While some may decry the tradeoff of resolution for sensitivity and dynamic range, the reality is that we live in a world dominated by displays that are either 1080p, slightly above, or share via web-based services that dramatically downscale images for bandwidth reasons. The question is then how much resolution is really necessary given predominately electronic displays start to finish and lack of much printing or enlargement. At least for my workflow, 4 or 5 MP seems more than adequate for most sharing, especially if it’s sharp and ends up having good dynamic range, and that’s still enough resolution to downsample to 1080p and get an even sharper-looking image. There’s also a case to be made for storage requirements which are lighter and so on, but most of that is obvious. The benefits from having more sensor sensitivity are also immediate – no need to fire the distracting flash in a restaurant or at a party, shorter exposure times with less blurring, quicker follow up shots, more accurate preview, and so on.

When I heard that HTC was taking their camera this direction, I was incredibly excited. Not only is this completely bucking the camera trend that just about every other OEM seems satisfied with marching down just for marketability reasons, it’s actually sound science and possibly the best way to end the megapixel myth in the smartphone space. Unfortunately the flip side is that, obviously, HTC now has to fight the megapixel myth head on. This is incredibly difficult to market to most normal consumers since megapixels is just about the only parameter ever exposed to them, and marketing was probably the biggest problem with HTC’s lineup last year. Conveying the Ultrapixel message will require more than a branded name and carefully avoiding talking about the fact that the camera is 4.0 MP on the box or online specifications (as it is now), it will require real education and an active role in building credibility in the imaging space. It will also require real demonstrable benefits to consumers in use cases that matter to them.

Battery Life and Charging Still Camera Analysis
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  • funnyhog - Sunday, April 14, 2013 - link

    Sigh .... you seems to have a misconception that Aluminium is a better material than Plastic composites? You do know that Aluminium is one of the softer and weaker and cheapest metal around? Unless they start using stainless steel, please tone down the exuberant over what is essential a very cheap and basic material in the engineering world.

    While I do not think Samsung uses top range composites (that are expensive AND can rival the properties of top range metals, although not usually all at the same time), from the reviews, it seems that the plastics used are consistently more scratch proof AND tougher than the aluminium used, which is so prone to dent and scuffing that you need to a cover over it at all times.
    Reply
  • Thud2 - Sunday, April 14, 2013 - link

    Sigh ....

    Harrumph...
    Reply
  • funnyhog - Sunday, April 14, 2013 - link

    As for the camera, you are right in saying that it is a compromise and trade off instead of a glowing fanboyish review like so many other reviewers. And in terms of trade off, it works if the person only wants to share over the web (and not to large screen format either, else it really really look horrible) or view their photos over small format viewers.

    But for most consumers who wants to print their photos, view it on their 17 inch HD laptop display or otherwise needs large format printout, it is a no go as the lack of details really really show, especially when the composition have lots of details or words/numbers. It is so bad that it can really detract from the overall quality of the photo, if it is enlarged and viewed over a large display or printed out onto just an A4 size paper. ( I tried both using the review images that claims to be the actual full size).
    Reply
  • repoman27 - Monday, April 15, 2013 - link

    You do realize there are no 17-inch laptops in existence with displays that have more pixels than this camera sensor? The only laptop with a screen resolution greater than 4 megapixels is the 15-inch MacBook Pro with Retina display. Also, prints up to 5"x9" could still be output at 150 LPI from a 300 DPI source.

    So yeah, the camera in this phone isn't exactly the same quality as a DSLR, but it is very well suited for "most consumers".
    Reply
  • peter123 - Sunday, April 14, 2013 - link

    You people need to calm down with the bashing of this review. Anandtech also reviewed SGS2 and it was highly praised, REMEMBER? If you don't accept that a company other than samsung can produce an excellent device than I'm sorry but you are a fanboy. HTC is an excellent device. Period. Reply
  • praftman - Sunday, April 14, 2013 - link

    17 Pages and only one on UI? How can I have just read every comment and yet nobody speaks with surprise about this amazing lack in an otherwise exceptional review?

    I'm purchasing this phone, and I like it for many of the same reasons Brian gives. I respect this review and yet…

    The UI is probably more important to the experience than all of the hardware; It's at least as important. Yet we receive one of the slimmest run-throughs of Sense 5.0 I've come across. I was hoping this indicated a companion review…but weeks in and there remains no Sense 5.0 review. What sacrifices are made by the lack of Jellybean 4.2.2? How do the quick-access functions differ from main competitors (silence, notifications, etc.)? How does the browser stack-up (it's an internet device after-all)? There is not even a quick breakdown or reminder of the main bullet-points for any of these significant topics, though apparently we need a refresher on all sorts of other things, hardware based of course.

    Moreover, the obvious competitor to this phone [GS4] has built its efforts with a particularly strong focus on software tweaks. But evaluating the phone's hardware with such heavy emphasis…the very battleground most-contended is largely ignored, making the real-world use of this review questionable. Did anyone really wonder if the HTC ONE was going for build-quality? Did we need this review to figure that out? It seems two-thirds of the review speaks the language of the obvious, the fact obfuscated in magnificent detail...Detail that almost no bearing on purchase-decision. I love that kind of detail, but I certainly wouldn't want in to substitute the meat of what determines a review's real-world value: Should I buy this?

    As a doc on technology, and to learn about the development of hardware, this is a fantastic piece. But in that sense [pun!] it is like a case-subject for technological education in general, industry education or even archiving. It's akin to the [deservedly beloved] engineerguyvideo series. That isn't for purchase decision, unless the reader is swayed by being lost in the brilliant and impressive information-overload, information that ultimately…isn't the right context.

    Context…that fails to address the blogosphere. We see no redress to the rumors of QC issues with gaps, no mentioning of availability or carrier-exclusivity. No discussion of carrier-comparison at all. No setting-the-record-straight with regard to inaccuracies in well-published reviews. No discussion on sticking points for many reviewers (such as the difficulty in customizing the home-screen with an awkward increase in dragging, pausing, dropping). …Part of the advantage to such a late review is to address all the other reviews and opinions now out there--but this one seems largely in a vaccum. Those concerns floated to the top, virally, for good reason. With each further review the gaps [pun!] they all share become more apparent. Here we have the best review to-date, but it's merely rehashing what we've already seen, just at a finer level. The community is asking questions this review still does not begin to address.

    Then there are the sort of flaws we'd expect when one reviewer attempts to 'do it all'. No single person designed this phone, and a single reviewer expecting to be minute in detail and *definitive* in their review is not likely to succeed. So we see the claim:

    …that softer metals are easier to machine; False in most situations.

    …of performance based on benchmarks Anand.com itself refutes with newer, better methodology. Odd that.

    ...that larger photosites are best to fight noise; Despite his expertise in this specific area Brian continues this simplistic and ultimately false refrain. Technology does not develop uniformly, and the nature of noise is multi-faceted. All things being equal bigger photosites are best. But…all things are not equal. Increasingly the best real-world strategy for fighting noise has been an *increase* in pixel count up to our current limits. This is from page 46 of the comment section, and many here would do well to read it:

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    sigsegv0x0b - Monday, April 08, 2013 - link

    There is only one problem with HTC's ultra pixels. DXO Mark seems to disagree

    http://www.dxomark.com/index.php/Publications/DxOM...
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    People have said the HTC ONE is just flash and form over function. Another iDevice [if you believe the common anti-fanperson's refrain]. I think it has stellar function, and again--this will be my next phone--but admittedly it does trade some real-world practicality for that build 'quality' [and here I thought quality was something built right, not something built to give the appearance of right]. The phone has a smaller screen [but I think that bezel will protect against errant contact] and they could have used that extra wiggle-room to protect the glass from all sides…instead they used the same glass expanse as the GS4, just with a large able unused portion. That's form over function...and over build-quality. No SD-card and the poor excuse they couldn't fit it in. The GS4 does. The Sony Xperia Z does, even though it's water-proof. The metal will not be comfortable in the sun (glare, hot to the touch) so when you place it on your accessory car-dock…make certain it isn't catching rays the whole time across its various edges. The metal will not be comfortable in the cold (now we have a reason not to wear gloves with this phone…and to wear gloves with this phone). The battery…ugh. I replace my phone every year and I still think this is an obvious misstep. Even the iPhone, while not user-replaceable, has a battery that a service technician can remove. It's clear that with the ONE many more phones will need to be fully replaced over otherwise minor fixes. I'd pay money to have this phone *not* constructed in this manner. I'll take a subtly rubberized exterior, please.

    This review is being celebrated as some sort of benchmark. It is…with regards to hardware. I'd hate to see the ball dropped so heavily on the software side by its blogger-imitators. This review, with its undue focus on the physical object, and its stark glossing over of the actual battlefield this phone faces, shares the same superficiality. Well made [review/phone]? Yep. Like an Armani Jacket. Functional [review/phone]? Not as much as it might have been…had the focus been on wearability.
    Reply
  • dyc4ha - Sunday, April 14, 2013 - link

    ill be honest i didnt read the whole thing, but just a quick comment: I believe the black version is the polycarbonate version, similar to the one x (someone correct me if im wrong) Reply
  • nerdstalker - Sunday, April 14, 2013 - link

    See my reply two posts below... :) Reply
  • Thud2 - Monday, April 15, 2013 - link

    I HAVE USED THE PHONE. It is extremely solid, really nice looking, VERY fast, Browser is very fast. Apps open instantly, screen is bright and sharp, it's very thin and fits the pocket well. Sound is better than any phone I've heard. Camera is fast and gets great shots that you would not be able to get with other phones. Stop fanboy trashing to start rumours. Nobody wants to hear your biased bull****. Reply
  • praftman - Monday, April 15, 2013 - link

    Maybe the comment system is messing up, or maybe you are responding to the wrong comment by accident, or maybe you just didn't read my [admittedly] lengthy comment...but I'm no fanboy. Not biased. Not much anything like what you're saying. Reply

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