New Samsung Galaxy S7 image sensor explained

by: Rob TriggsFebruary 23, 2016
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Samsung-Galaxy-S7-Edge-19

Samsung has long been a notable player in the mobile image sensor game and the company is taking a new approach to photography with the introduction of its Galaxy S7 smartphone range. The company is throwing out its high pixel count 16 megapixel sensor from last year’s flagships in favour of a lower resolution 12 megapixel sensor that features larger individual pixels. So let’s explore why Samsung is making this change.

Why use larger pixels?

We are regularly told, perhaps wrongly, that smartphone image sensors are catching up with the features and quality offered by much more expensive pieces of equipment. However, the fact is that the compact size of smartphone camera components leaves designers having to make compromises. Often we have seen engineers increase sensor resolutions in an attempt hide noise and imperfections, but this comes at the expense of colour quality and low-light performance. Samsung looks to be tackling this particular trade-off head-on, by reducing the megapixel count and opting for larger pixel sizes.

As photography enthusiasts are probably aware, it isn’t the megapixel count that matters so much for capturing high quality imagery. Extra pixels are handy for cropping down images at a later date, and it might interest you to know that just 6 megapixels is enough data for a detailed A4 sized picture print out. Instead it’s the size of actual image sensor and the ability of the photosites (or sensor pixels) to capture enough light that is highly important to image quality.

High-end smartphone image sensors are smaller than 30mm2, making them notable smaller than DSLR sensors.

Techspot High-end smartphone image sensors are typical around or smaller than 25mm2 (1/2.5″), making them notable smaller than top of the line image sensors found in DSLR cameras.

Simply put, larger image sensor sizes allow for bigger photosites, which means more light per pixel. Typically, this results in a superior dynamic range, less noise, and better low light performance than smaller image sensors with an overly high pixel count. Of course, compact smartphone form factors mean that we’ll never have quite enough space to match DSLR sensor sizes, so compromises have to be made to find the right balance between noise, resolution and low light performance. Rather than pursuing additional resolution, Samsung is looking to increase image quality by maximising the space available for each photosite.

Of course, CMOS image sensor design is a little more complicated than just that. Backplane electronics and isolation between pixels can have a substantial impact on attributes such as noise due to crosstalk between pixels. The lens placed on top of the sensor and the image signal processor used to interpret the data are equally important too. Unfortunately, Samsung hasn’t spilt enough beans for us to piece together everything that is going on inside its latest smartphone camera, but here’s what we do know.

Samsung’s sensor specs

Samsung has increased its pixel size from 1.0um in its Isocell sensors up to 1.4µm in the Galaxy S7, allowing for additional light capture in each photosite. This marks a 56 percent increase in pixel size compared with the Galaxy S6.

samsung galaxy s7 first look aa-19

This isn’t quite as large as the 2.0µm sizes found inside HTC’s Ultrapixel technology and is still slightly smaller than the 1.55µm photosites found inside the Nexis 6P’s sensor, which was a consistently excellent performer in our own testing. However, Samsung has also greatly increased the size of the opening in the accompanying lens so that additional light can make its way to the sensor. The Samsung Galaxy S7’s lens has an aperture of F/1.7, up from the F/1.9 aperture in the Galaxy S6’s 16 megapixel camera, offering up to 25 percent more brightness.

Combined, Samsung states that this allows the camera in the Galaxy S7 and S7 Edge to capture 95 percent more light compared with its predecessor, which should greatly improve low light performance and help to de-noise images, a common problem with small smartphone sensors.

The future of fast focusing

The extent of Samsung’s changes with its new image sensor don’t just stop at light capture. The company is also the first to implement dual-pixel on-chip phase detection across every single pixel in its sensor.

This phase autofocus technology has been used in some DSLR camera sensors and works by detecting the phase of light received at two separate pixel locations. This information can then be used to focus in on a specific object or part of the frame, in a way not too dissimilar to the way that the human eye perceives depth.

Galaxy Dual Pixel auto focus

Other image sensors, such as high-end Sony Exmor RS models, implement a small number of phase detection diodes across the sensor, but these usually account for around just one percent of pixels. Samsung is the first company to implement phase detection across every pixel in its sensor. The major benefit here is that focusing can be achieved much faster than before and focus time is less dependent on the content of pixels located in certain places on the sensor. Samsung shows off just how fast the Galaxy S7 (right) can focus compared with the Galaxy S6 (left) in the video below:

The Samsung Galaxy S7 has certainly set itself up with quite a different take on photography than the company’s previous flagship models, and the theory sounds right on paper to really bump up the picture quality. Ultimately though, it’s the final image quality that matters the most and there’s more to a good picture than just the sensor. We’re going to be putting the handset’s camera through plenty of testing when it comes do doing a full review.

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  • staylow

    Low light shots good enough to put the point and shoot in the grave finally? If it can take shots like my 2yr old Sony WS50 in low light then “maybe” I’ll spend the scratch for a 700 USD phone. Till then there are entirely too many solid options for 4 bills or less.

    • Josiah

      Sony xperia Z5 can capture lots of low light photo, because of the ISO12800 , you can even capture those extremely dark places that our eyes cannot see.

      • das

        sony ? no one cares

      • TheDude

        Oh so you can take photos with 12800ISO, how much noise do you get in them?
        A shitload.

        If you knew anything about photography then you’d know, its preferable not to take photos with high iso.

        • Josiah

          But it doesn’t produce that much noise. only 65% increase in noise from ISO 300 to 12800

  • aaloo

    Pretty amazing how android coverage is so skewed towards one OEM despite so many “choices” available. There are 10 articles on Samsung for one article on the rest.

  • Sayed ahamed

    The smartphone photography has a long way to go. And the future sure looks bright ( pun intended) with all the new technologies being available . as processor gains reduce camera fidelity will matter most along with the display going forward towards future smartphone. Also quantum film which allows for electrical isolation between pixels instead of physical barriers , oppo’s microelectromechanical OIS , dual photodiode PDAF like on s7 and CSS on the G4 and G5 . and yeah let’s not forget wonder material graphene which would allow for lenses to 1nm thin and focus on objects as small as 200 nm. The future sure looks inviting but it’ll happen eventually

  • jendrush

    S7 camera looks amazing, but i would like to have 16:9 proportion, not 4:3 :(

    • Josiah

      Sony has a dual aspect ratio sensor on their Z5. Even the high pixel count, the Z5 can capture very dark areas that even our eyes cannot see

    • Angel

      All 16:9 sensors are cropped. Only 1:1 sensors are not cropped. Lenses are circular and a 1:1 square has the maximum area coverage. So, 4:3 is preferable as is closer to 1:1.

      • jendrush

        Reasonable argument:)

      • nickmgray

        Actually, HTC Ultra Pixelmator sensor is 16:9. It was used as the main sensor in the M7 and M8 and is prominently featured as the front facing camera on over a dozen HTC phones. So it is possible.

  • Josiah

    Sony already done all these features here Except sd820 sammy is late

    • das

      did u even read the article ? they did not

  • amd

    Hi android authority. Please correct this article. Samsung not using any Samsung image sensor for galaxy s7 or s7 edge. They use Sony sensors. Last year Sony released this technology. And Samsung use dual pixel name for that for marketing. Please don’t write wrong information

    • KenanSadhu

      Some users in samsung forum has been reporting that their S7 is using Samsung’s ISOCELL sensor. It is actually reporting the truth. Same thing happened last year with the S6.